Really? He'd cut out a man's heart, a stranger's heart, if the Lord Protector told him to?

What if it were a friend's heart? Because Auror Crouch and Professor Dolohov were the ones who brought Mr Selwyn to be tortured and killed. And he was a friend of theirs.

The Lord Protector makes his closest followers do TERRIBLE THINGS. Sometimes to muggles, sometimes to 'traitors,' sometimes to EACH OTHER.