@Dill While what you said is definitely worth considering, you have to consider that doing these types of things makes keeping the peace a lot harder than it needs to be. We shouldn't have to be called to fix something that was caused by you. For example, while flamethrowers aren't "illegal" (for lack of a better term), we had almost instantly gotten a report of someone setting 2nd Floor Lobby on fire. While others could argue that it wasn't you that did this, you still enabled it. Like it or not.
But while the weapons shop was the bulk of the report, the primary motivator for this was the unbanning and unarresting of the trooper. You didn't bother to talk to the CG about why he got arrested, like many admins would. When the trooper was arrested for ERP, it was an AOS. CG don't TALK to people when there's an AOS on them. They carry out the arrest, put out the AR, and fill out the form.
The way you carried out the punishment for him (false or not) was completely unprofessional, because, again, you didn't talk to anyone. You just teleported him out without saying a word. The same pretty much goes with the ban. There was no discussion about it, you just unbanned him. You completely undermined what the admin was trying to do when it was an issue that should have been taken to the ban appeals.
As for CG not telling you that things were getting out of hand, you know your rules and how to uphold them. CG shouldn't have to tell you when you go too far because, as an Owner, you should know your own boundaries and why this would probably make it hard on them.
As for your edit, from what I understand, ERP is an instant ban without warning. Perhaps the admin was doing what he thought was right. The same can be said for you, sure, but if an AOS is called, I imagine the least you can do is respect it and give staff a chance to investigate the matter rather than instantly acting on it out of your own volition and (once again) undermining both the admin and the CG.
EDIT: Another reason CG probably wouldn't approach you is because of your status on the server. The newer ones would be intimidated while the more seasoned ones let you get away with it because it's "not worth the trouble".