It's a fair question, bro. All I can see is maybe this. Like, he knew it was a gamble, but he was hoping by claiming cop he could get the real cop to oust themselves and let the other mafia get a bead on 'em. No way it's a coincidence that Chiaki's cop role got blocked the same night after she came out as a cop. If people believed him, then they could night kill Chiaki, Sakura, or Sonia like Byakuya wanted. If no one buys it, then he's a goner, but the other mafia now know who they can block and can add a kill. So, since no one bought his story, they blocked Chiaki's move and killed off Kyoko. It's a number's game, man. Sacrifice one mafia to neutralize two students.
Plus there's this.
That bear is crazy, man. He loves makin' chaos, and there's no way Byakuya could've calculated that the bear would do somethin' like give out a special one time power. Dude probably thought it was a safe bet at first. Even if he lost, mafia is still lookin' strong. But not after I got lucky with that special ability, and by then it was too late.
The way I see it, like, we probably still have two scum left. One that can role block and probably just a goon dude. We're catchin' a break here for sure man, but I need you to have faith in me like I'm havin' faith in you, Sakura and Chiaki. She says you're good, and after her and Byakuya's cop situation it seems like she's bein' honest. So I'll leave you guys alone. Scouts honor n stuff, bro.
I know Celeste is bad news, so she's a goner in my book. After that I've only got eyes for Nekomaru, man. Unless he can really prove himself clean. That's how I'm playin' this one.