Seems like the note in the syntax thread is incorrect, or at least incomplete, because from what I’ve seen (including this thread and personal experience) unless you get hit with a total suspension (can’t see the forums at all) you can still get trust 3, even if you get a silence for a little bit. I think some things about the inner workings of the forum are still unclear even to Blizzard. See this thread on CS where the CS forum rep was told that the forums account/profile/trust levels are tied to character ID, where I tested and proved that isn’t the case:
I’d guess it’ll take a while for them to have everything completely figured out.