I moderated a forum myself a few scores of years back and every once in a while discussions like these popped up.
Shadowstalker16: Or if those sites baited you in with promises of lack of certain restrictions but imposed them later on. There are obligations to fulfill what's said in the TOS of sites, which aren't legally binding, but one has to keep in mind those rules were put there for the site administration itself, and violation of those is basically lying.
It's perfectly possible for forum hosts to set some guidelines, find out later that in practice those guidelines aren't sufficient to keep things running smoothly and amend the guidelines accordingly. When people pull the "lying"-accusation, they do so by pretending the new guidelines had always been in place. In truth, what they call "lying" is simply "changing one's mind". There's a subtle, yet important difference there.
Shadowstalker16: Many of these bans dished out on reddit or twitter are random and are the exceptions to to the banning of rule breakers. Evallion(?) is a great example of that. Out of the many TOS violating channels out there, her's was the only one banned. Plenty of others exist as well.
A good comparison to this situation is how the police doesn't go after every single person who drives faster than the current speed limit allows. Just because they let 10 people off the hook each day doesn't mean person 11's rights were violated when they slap him with a speeding ticket. The other 10 simply got lucky.
Shadowstalker16: In the end, its their site and rules, but its come to the situation where they don't obey their own rules and still selectively ban some for breaking those rules. In that scenario, where absolutism is the norm and only some dissent is removed, its practically censorship,
although not in principle because the rights weren't probably
there in the first place. In the end, a site admin doesn't have to abide by his own rules, just like a house owner can get plastered in his own home, yet is perfectly in his rights to expect houseguests not to get plastered under his roof. That's the difference between hosts and guests. Anyway, the bolded part of your quote is all there is to it when it comes to guests being entitled to special privileges on a forum/webservice they do not own.