His prodding of Bwom to get her to claim strikes me as vaguely scummy. Bwom was unlikely to refuse someone directly asking her to do something she could do, and lo and behold, she did. Without hesitation. And somehow Cereal found that suspicious. This whole interaction gave me odd vibes from him.
Dupti also stated the info for his stone had been removed from his QT after it was stolen, so I feel it is safe to assume Cereal is not Thanos; and telling the truth about losing his stone (since Dupti later confirmed stolen stones remove info from QT; unless Cereal has a teammate who lost a stone and he thereby knew through association) - either way I think we can trust the info given about Thanos; as even scum would not have motivation I can see to withhold info on/lie about Thanos. (Unless we are given reason to believe Thanos has contact / works with the other scum, in which case it is possible this is a ballsy play to set himself up to not be suspected.)
I had him in my mind as firmly town due to his soft character claim. But the more of those I see, the less they feel like they mean much. And without that on the scales, I am less convinced. His info about the stone was helpful, but it would be easy for a scum to share such a thing for town cred; and we have no assurances scum did not start with stones.