Pre-Emptive Sensitivity Rebuttal: This was one of the few roles the guy had in movies. It was funny. It was also a first; I don't think anyone had ever played himself as a serial killer before. (And not too many since then, either. I can't think of any, but I imagine someone must have swiped the idea since then. I know Davey Jones of the Monkees filmed that part of The Brady Bunch where he drug-raped Marcia, but they never aired that, selling out with the "happy ending" we're all used to.)
Obviously the guy contemplated this clip, like anything else he did, would live beyond him. So come on, what's the harm in Merv Griffin delivering one more laugh?