On the fourth episode of Andor, "Aldhani", Cassian (Diego Luna) mentioned his desire of not having to keep looking over his shoulder forever as a reason not to join Luthen Rael (Stellan Skarsgard) in the Rebellion. Three episodes later, "Announcements" shows us how well that has been going for him. In the aftermath of the attack to the Imperial garrison in Aldhani, Cassian took the money he was owed and set out to pay out the debts he had when he ran away from Ferrix. He insists on trying to lie low and keep his head down, but that is proving difficult to maintain.
What Cassian obviously failed to see is the context he lives in. As the Empire tightens its fist around the galaxy, people gradually lose more of their freedom and basic rights, and Aldhani only made things worse. Everywhere people are getting arrested for just looking sideways at stormtroopers or just looking suspicious. Cassian, of course, had plenty of reason to look over his shoulder, such as the murders on Morlana One, the incident on Ferrix, and now also for the Aldhani attack. What he still hasn't understood is that, in times such as these, it's simply impossible to stay neutral, try as he might.
There Is Nowhere to Hide in the Galaxy From the Empire
What happened on Aldhani in the last episode had repercussions all around the galaxy. The plan carried out by Vel Sartha (Faye Marsay) and her band of ragtag rebels faced many problems, but was still seen as a success by Luthen because its goal wasn't just to steal a quarterly payroll for an entire Imperial sector. It was to make an announcement. That was the first time the Empire had its power challenged in such a public fashion, visible for all to see. For them, it was embarrassing and showed vulnerability, which is something that simply cannot be allowed to happen in a regime that perpetuates itself on the basis of fear.
One of the initial scenes of the last episode shows the head of the Imperial Security Bureau (ISB), Colonel Wullf Yularen (Malcolm Sinclair), making it clear to his agents and supervisors that, from now on, they all have carte blanche to operate how they see fit in order to prevent further threats to Imperial authority from ever seeing the light of day. To make it so, a new set of policies and directives were implemented by Emperor Palpatine himself, a package that looks a lot like the Patriot Act in space. So it's not just opposition politicians such as Mon Mothma (Genevieve O'Reilly) that find themselves under surveillance, it's every citizen, everywhere.
At first, Cassian may think that might not make much difference for him when it's truly the other way around. The first arc of Andor showed us precisely the importance of taking sides and protecting one's community against an overwhelming foreign force. We saw that in Kenari as much as in Ferrix, in fact. Sometimes you may even know you are going to lose the fight, but there are always alternatives to fighting, as Alec Guinness' Obi-Wan Kenobi put so well in A New Hope.
For the people in Ferrix, that alternative is resistance. A silent and weary resistance, but an active one nonetheless. When Cassian sees Maarva explicitly taking sides and refusing to run away with him, he doesn't really understand how she can do that, or even why it's important to do so. We still have much to learn about Maarva's past, but we know she is one of the key elements in Cassian's upbringing and his espionage background. She taught him the basics of hiding in plain sight and protecting his identity.
By Not Making a Choice, You Side With the Oppressors
Unfortunately, choosing the side of the oppressor is extremely easy, as it only requires inaction. You don't have to wrap yourself in banners, carry signs, or protest defiantly. You simply do nothing. While that happens, the oppressor takes their time to further establish themselves as the dominant system and eliminate opposition. One might even argue that "if you have done nothing wrong, you have nothing to fear," but that's not really how it works when push comes to shove. "Doing nothing wrong" is simply keeping one's head down while injustice is carried out around them. It's an extremely selfish thing to say, especially if one has already lived through an authoritarian regime.
Cassian is slowly learning that lesson. In Aldhani, his exchanges with Nemik (Alex Lawther) were a good first step, but he still needs to gather impulse for the big leap towards turning into a freedom fighter we all know he will eventually make. His arrest should be another step in that direction, as he was detained for the only crime he didn't commit. Even if he looks extremely suspicious, that should never be a reason for arresting someone.
The Rebellion Will Force Cassian to Take a Side
Despite being brought up by two people with strong political views, Cassian still hesitates when faced with situations of injustice. An important scene in "Announcements" was the flashback of his father Clem's (Gary Beadle) execution. As the two of them watch a military parade in Ferrix, someone shouts, "Long live the Republic," meaning that, despite the white Phase-2 Clone Armor, that was actually the early days of the Empire. Someone was standing up against this newly instated oppression and would soon pay the ultimate price. Clem tried to intervene, only to be mistaken for the person who threw the rock and ends up executed.
We are hardwired to instantly see two equal parts when a conflict situation arises, so the most common reflex is to put the rock-throwing protestor at the same level as the armored and armed stormtrooper. Aggression is never the way to go, and it goes without saying that no rock should have been thrown in the first place. But once it was, it's clear that the civilian on the street is no equal match for a military force.
Cassian still doesn't completely understand what happened. What Clem was doing wasn't trying to find a middle ground or apologize to anyone, he was trying to prevent bloodshed. He was taking a side. He was trying to save that person, and if the oppressor has guns and is willing to use them, preventing loss of life is a powerful act of resistance. This happened while the Empire was establishing its structure and oppression, now that it has a firm grip on the galaxy, it's best that Cassian learn his lesson sooner rather than later and pick a side.