Bruce LaBruce is a fairly successful contemporary gay photographer/videomaker from Toronto. Seems to have a pretty strong bent (no pun intended) toward the skinhead/punk look.
I understand that it goes back to the '60’s, Exapno Mapcase, but that doesn’t mean that Johnny Carson couldn’t have been the one who popularized the term. I don’t remember hearing it used before hearing it in Carson’s monologues. In any case, Johnny Carson was host of The Tonight Show from 1962 to 1992, so he was (apparently) around at the time that the use of “Bruce” in this way started.
I once heard someone else conjecture that the use started from Wertham’s claims about Batman in his book, but that never struck me as likely.
So, is the use of “Bruce” in this way largely obsolete these days? I don’t think I’ve heard anyone use it since the '80’s.