Mafia 110. Heckelia

Well, why not? I understand if 10 people suddenly voted for him after me, and you would defend him. But in this case, it was clear that he wouldn't be executed, so why not "defend" him?

That's exactly why people like you will dig in, start connecting one thing to another, look for clues, and find patterns. Never, not a single sane mafia player, who doesn't have strong connections within the town, will suddenly appear out of nowhere and start arguing against executing someone based on their own evidence, especially when there are no other candidates, even if they feel that this player won't be executed. They won't gain anything from it, but they could lose a lot. If you've played as a mafia member, you know that it's in their best interest for the town to quickly eliminate the other mafia members and each other, and for the night phase to focus on the suspected town members, not on them. And no amount of flattery will make a difference when solid factors like checks, blocks, and correct evidence are brought against them.