Jim,
For once am in complete agreement.
Just a suggestion.
Whilst we all have our minor differences on a definition, we actually have a lot in common.
There is sufficient expertise on Mudcat and some of the other ballad/trad song forums to formulate our own WORKING definition of 'traditional song'. Instead of bickering over minor differences let's explore what we can agree on. Obviously some of the more wacky ideas will differ but finding agreement could be very useful and helpful.
So what I'm proposing is a MUDCAT definition to help those genuinely confused by the whole affair.
(BTW I don't include 'FOLK' in this. I think we've got to accept that the word has a much wider definition than most of us would like, but we are in the minority and it's about time we accepted that.)

One thing I'm sure we could get majority concensus on right away is a song's origin is a total irrelevance to any definition. Okay that's got the ball rolling hopefully.

One other thing, a working definition doesn't necessarily have to have hard and fast boundaries to be useful.