Another axiom could be that for a cryptocurrency to remain censorship-resistant it is vital that it can be safely run behind Tor. Finally, we could add an axiom that states that some of the new code in Bitcoin XT makes it difficult to run Bitcoin XT safely behind Tor.
First of all, I don't agree with OP. There are more choices. But, even if you make a good point, this is the worst axiom you could choose. You have to proof(or make a logical argument, if you prefer that terminology) , that there is code, that makes it hard to run Bitcoin XT safely behind Tor. An axiom should be something, that can't be proven, not something, you are just too lazy to proof.
Also attacking an axiom is nothing that is somehow forbidden(otherwise I could just take absurd axioms like "the sky is red") as a "logician" you should know that.