This is all hilarious reading to an internet searcher who has stumbled on this colloquy only after reading a number of other accounts.   For Muttman, it might help to note that Paul Stookey (of PPM) actually describes how he came up with what was recordered - he was working finger exercises trying to bring in an old wassling tune (Hey ho) mixed with the (as we learn elsewhere) separate souling tradition from the end of the Celtic year (definitely related to the later Halloween).   They only added the piece from God Rest Ye Merry Gentleman when they were practicing for the recording - so the piece at the end has nothing to do with the middle and reveals nothing about the origin of the title.

It seems we have soul sandwi(t)ch, with the end of the Celtic year a soalin' (PPM intentional misspelling) as the meat and end of the year Christian/Wasseling tradition as the bread.   Apparently, some are finding that mix hard to swallow.   Me, I just enjoy playing the very engaging guitar exercise, and getting away with singing about ancient Celtic rituals at this time of year.

JB