I think that's getting into the differance between entitled to and reasonable expectation again.
The company own the board - I am not *entitled* to talk about anything their - it's their board, they could kick me out of a bar for picking a fight, so I assume they can kick me off a BBS.
I have a reasonable expectation that's not going to happen, partly based on the rules of the road previously established, and partly based of the fact that, if the topic is a subject of legitimate debate, then it is foolish for a company to bar me from discussing it in their personal forum where they have the home court advantage and the opportunity to present their case to a sympathetic audience, and so bring it into a wider discussion in territory they have no control over.
As President Johnson put it, "It's better to have your enemies inside the tent pissing out than outside the tent pissing in" - {G}.
There are of course certain kinds of actions where a business or agency can do something for good reason or no reason (Typically firing someone), but not for a restricted list of bad reasons (Say, firing someone after they file a harrassment claim), and there are physical private venues that are public for purposes of limiting the control the managment can exercise over speech, so it is vaguely possible that banning discussion in a forum would be a legal issue on that basis, but I kinda doubt it.
But it's still foolish on their part - there's no outcome that makes the situation *better* for them than me discussing it on their home court.
Jonnan