Masons aren't really a terribly uncommon role. They are basically the equivalent of an Encrypter for Mafia.

A cop investigating himself first is actually a valid move because if he shows up as guilty, then he is either Random, Insane, or Paranoid. 2 of those 3 are bad. (Insane isn't as bad once you know that's what you are since it just produces opposite results.)

I doubt he would be Random because then I could castrate Cyber.