The answer is probability. In a role madness game, you have 5 time.
What does 5 time mean
Let’s say 2 of those have pure town roles, that’s 2/9 possible roles. He has 7 town roles he could claim, but odds are bad. Compare that to the town/mafia list. Advantage of that list is that if scum have it, town don’t have it, so he could be truly a scum JOAT. Plus the list is far bigger so easier to fake claim
Bigger list, means less chance of him getting caught on a more "townie" sounding role though. Again he didn't have to claim, I dont think anyone was pushing for his role, just character. There's a ton of more townie sounding roles on that list than JOAT, and I don't think chances are super high he would get CC'ed by most of them. Maybe with cop or doctor, assuming you don't think bullish randomized it like he said.