You're not being censored as you just proved by opening this thread. JG has the right to create self-moderated threads and lock them whenever he wants. You have the right to open a "Reeeee" thread in response, which is exactly what this thread is.
I know what the trust system is all about
You pretty clearly do not, because if you did, this wouldn't even be a question:
Sub-question for discussion:
Does a member who censors the community from further discussion and locks threads to have the last (misinformative) say, deserve a trust feedback tag?
The answer is
no so long as the thread in question has nothing to do with trading on the forum.
Is it a separate incident requiring a separate thread?
No, because it is the same problem - the OP is trying to censor further conversation to prevent further damage to their reputation.
There's a pretty big difference which you are ignoring: BetKing is trying to promote a casino and Jolly Good isn't promoting anything. If a service provider locks a thread in the face of criticism, then that may or may not inspire mistrust. But even that is context-dependent: a completely above-board business might just be locking a thread because they are tired of dealing with trolls.
The point is there are a lot of nuances in determining the appropriateness of trust feedback and making sweeping generalizations usually isn't a good idea.
At least you removed your negative rating on JG, that's a good start.