No...it was smart. Probably the first smart move he's made all game, actually. Even if he claimed to have been framed, it wouldn't have come off as believable in the least and he would have most likely been executed anyway. This way, he's set up our path to victory.

Don't you get it? If the prey accepts his word at face value, that means they'll stop looking for the convert...which means that Kirigiri, who had caught two hunters beforehand and has proven her role multiple times, is now completely clear. They'll be trusting her with information - including who the new watcher is, as well as any other roles we may be missing. We don't need Naegi to win. We only need Kirigiri.