"Murder Hobo" is OLD! I am really not sure HOW old, but I was playing in the 70's, so I probably heard it approximately around the time it made the rounds, and that was definitely in the early 80's or earlier. It was just one of those things that 'appeared'. I just don't recall from where, possibly some article in some publication? UseNet actually sounds like a VERY good possibility, as that was about the only way in the pre-Web days for stuff to get around, outside of print.
So, the more I think about it, the more I am confident that it was something derived from UseNet, and/or the BBS community, which were pretty synonymous in those days. I was in college in the early 80's and we did have access to UseNet. There was a LOT of RPG stuff on there! Actually quite a lot of it migrated into the greater online community since then, like most of the debates about alignment, and the discussions of RPG theory (ala Forge and such).