Please don't refer to Ferdinand Ambach, the man who beat a 69-year-old to death, as the 'banjo killer'. This isn't a western or Dick Tracy. Clayton Weatherston wasn't referred to as the 'scissors killer'. Perhaps Weatherston's case wasn't as 'hilarious' as Ambach's, seeing the former didn't use a musical instrument (or kill a gay person), but there's no reason to belittle this case.
PS When you say that Ambach killed his victim "after he received unwanted sexual advances", you seem to have forgotten the word 'allegedly'. The court didn't find that was true, because that wasn't its job. I can't help but note that the opening paragraph on Weatherston's sentencing didn't talk about him killing Sophie Elliott after she attacked him with the scissors. It seems that you think these two objectionable defenses are different. They're not.