I can fall into a barrel of tar, get a cut on rusty metal and contract tetanus while being screamed at by a fat mermaid and i could still name like 4 ways how come a Mason claim can be bad
To elaborate, I'm not saying there's 0 chance a mason claim can be faked. Default assumption is that it's pretty decent claim, though, as the other assumption is two mafia tying themselves together, and risk being counterclaimed, quite risky.
HOWEVER
I fail to see anything Drago and his buddy could put forth, as additional info, that trumps the reliability of a mason claim.
Therefore Muugen rolefishing in this circumstance is categorically, always bad.