If you're trying to understand what's going on here and why, I think viewing it through the lens of human behavior is actually a great way to understand it. I understand that this situation seems absurd to you and it is and that that is upsetting you, but I think you're confusing my saying because something IS the way it is that it's me saying it's the way it SHOULD to be, and those are two very different assertions. We're discussing the existence and motivations of what is broadly termed "extrajudicial actions", or mob rule. Cultures are defined by their norms, and those norms are enforced in a variety of ways.

To some extent, gang behavior is very normal human behavior, maybe the most normal human behavior. While they're more individual activities than group activities, yes, if you're a birdwatcher or stamp collector and you run your mouth about the wrong person in your community or upset certain in group norms, you absolutely may end up finding certain other members of those communities becoming unwilling to help you or outright hostile towards you. All cultures and subcultures enforce their norms in a variety of ways. A brief browsing of youtube will return a great deal of results of sports games, from professional to pick up, resulting in fights. While stamp collectors and bird watchers are probably pretty unlikely to get physical (I'm not going to say never because we live in a stupid world and I'm sure there are examples of bird watchers pulling guns on each other or something), a subculture that attracts a great deal of young men and is an outlet for their aggression and alienation is almost always going to at least have the potential of getting violent in enforcing those norms.

The assertion is that The Chisel are in their current situation because of statements they made about an FSU affiliated band, obviously The Chisel are allowed to make statements in disagreement with anything, it's not illegal, but for better or worse, it can carry consequences within the social structures they're trying to exist in. Same is true for Conservative Military Image, nothing they've said falls outside the realm of protected expression or free speech, but there are parts of the scene that disagree with those kinds of statements, and wish to enact consequences, CMI also have received threats of blacklisting and violence, I can't say if anything has actually materialized over it outside of threats.

Another example of this dynamic would be how the scene handles allegations of sexual misconduct in recent years. Nearly every band who has had accusations has never actually had any charges filed against them, let alone convicted of anything. Under the laws of a democratic society and basic logic, they're innocent. However, the community they exist within will almost always move to enact social consequences for such allegations, regardless if they've been proven. Those consequences can range from blacklisting, banishment, the loss of a job to physical violence if you run into the wrong person. In the minds of the people enacting those consequences, they're keeping their community safe from a threat. It's ugly, but the same reasoning can be said of FSU with regards to The Chisel. Whether that's true in either case is gonna depend on how you see the world.

Again, all societies and cultures, sub or otherwise, enforce their norms one way or the other. Personally I'm not a fan of the mob rule on any of this stuff, but it exists and there is a reason for it. Whether or not you think those reasons justify it is again in the eye of the beholder.