Mafia can interfere because a strong player, and they themselves, can be quickly killed (if they are not Mafia). City defenders often come to protect you for the same reason. But, this Mafia has an Achilles' heel...
So, almost 80% of the time someone will protect you (Hector might be among them), therefore it is beneficial for the Mafia to send Achilles to kill you, who not only ignores the protection but can also kill the protector, in the form of Hector, in one turn. As a result, in one turn, they kill both a good player and a strong role, so think for yourself.