This is a free privately owned forum by Agoracom and they have the right to moderate the forum. No judge would ever force such a company to open the flood gates to all comers and certainly aren't in the business of determining what messages warrant removal.
Whether the moderators decisions are fair, is always up for debate, but those decisions are well within the rights of Agoracom and its moderators. If you feel slighted you certainly do have the right to protest those message removals and bannings publicly in a peaceful manner if you so choose.
S.