Yeah, in many games, a role cop would seem like a scum role - but weigh it out here:
Role cop vs Role block
Which one of those is more likely to be scum with what they know about this game? One exists to verify and the other to shut down. In THIS game, even with two scum-possible roles, if they look beyond historical meta and instead at THIS game, Blarg's role makes total sense as town to help town find the right people in a game of Which One Of These Is Not Like The Other.
But that isn't this game, which has a clear theme to it despite being "just mafia." That's what I'm saying. Their logic is fine, based on the GAFia meta and on the abstract. In this specific case, though, the check role seems MUCH more likely to be town. Fits the theme.
But this idea of roleblocker plus role cop both as scum is gonna get them.