He is telling somebody that The Lounge is not a debate forum, which is obviously true.
It may not be appropriate to have FE debate there, since there is a dedicated forum for that. But having a debate on other topics is certainly not against the rules. Regardless, he was asked more than once to keep his posts on topic, but insists on going back to complaining about rules, moderation, whatever it may be after being specifically asked to stop. Someone else can come in and reevaluate if they would like.