StarEngineer isn't invincible, and he isn't defenseless. StarEngineer's stare can only affect one target at a time and he cannot spam his ability. If he transforms the wrong target, the victim will try to retaliate. If defeated, his victims return to normal, but it doesn't always happen like that. Sometimes they are formed into hybrids a cross between man and prop this happened when Rappy defeated him and Sniper (who was turned into a duck) only regained his head.