Ok, let's break this down a little further.
Fact: You have said you are the mason leader
Fact: I have not directly contradicted you, but I have insinuated that you may not be telling the truth. Unfortunately, I cannot or do not wish to reveal my position to actually contradict you.
NOT A FACT: It would be VERY stupid to contradict you if I were a Mason. Doing so would put down into some peoples minds as to your real identity, but the real fact is that I cannot PROVE you are not Mafia, I can only make a compelling argument. All this really accomplishes though is to confirm to YOU who is a Mason, thus putting a huge target on myself.
NOT A FACT: I am providing cover for no one, I am simply pointing out that we cannot accept your word to be gospel, because there is a very legitimate circumstance where you could be lying.
Let me lay this scenario out very clearly one more time. I apologize if I was not able to clearly explain what may be occurring here.
Theoretical example:
A mafia member (we will call him Dixy) decides he wants to blow the cover of the Masons early in the game. As a result, he claims to be a Mason himself, thus forcing the real Masons to refute his claim and expose themselves. Now Dixy has ascertained very early on the identity of one of the Masons, perhaps multiple Masons if the Masons act foolishly. Here's the most clever part of this tactic though. There is really no downside for Dixy. If the Masons do NOT refute his claim, he has given himself an EXCELLENT cover identity as the Mason leader that nearly the majority of the rest of the players have to accept as fact. No one has refuted him so he must be the Mason leader. No need to ever Lynch him and he can then begin controlling people as pawns.
Absolute worst case scenario for Dixy is that there is doubt in the minds of some players as to who is the real Mason and who is the Mafia liar, as no one can really prove it one way or the other. This isn't so bad of a scenario though, as everyone's roles are in doubt at this point of the game, so Dixy would simply be back at point A.
You see, its an extremely clever tactic that I do not want to let go unnoticed. Now, we could be dealing with a situation where Dixy is in fact telling the truth. Although, the advantages of doing that are much smaller than the harm he would be doing to himself, so I can't really believe that is what we are seeing here. Dixy might be setting himself up to be the sacrificial lamb though?!? *shrugs* I think it'll hurt the town more than it'll help him, but Dixy obviously disagrees with me on this point.