Just leave it up to the host who should specifically say in their OP whether theyíre allowing a tie or not or will arbitrarily award somebody a victory they didnít earn just because thereís less of them.
If it's stated in the OP town have to win before a 1v1 tie, scum would be earning their win in that case because it's literally their win condition in that case. Like with Odo's OP. Just stating for future reference, not anything previous that's already been discussed.
I don't think everyone will follow what's decided here, even if you get consensus. That would box people in too much.
I don't want to regulate everything, just make some thing standard, like a role resolution order and such to prevent varying opinions causing drama and arguments, and to make a reference for those who are hosting