It became really clear that he isn't a folklorist/ethnomusicologist,

In which case, GUEST, you missed the point entirely. At no point have I claimed to be either of those things, though as a Folk Musician (which is to say one who sings & plays as part of the wider Revival) I do have more than a passing interest in the subjects.

But, for the sake of clarification...

When I say that a Jim Eldon performance of a pop song is Folk I'm talking about the wider remits of the Revival Scene in the UK today which is not very concerned with The Tradition per se, but a particular way of dealing with al manner of Popular Idioms in terms of its Spirit. It's akin to Jane Turriff singing a Jimmie Rodgers song - it touches a broader cultural ambience of what most of the population experience by way of a Common Vernacular Musical Usage beyond the specialist enthusiasms of a small number of habitues in a small corner of The Revival. Traditional Singers were part of that wider culture too; Folk Singers likewise, but when Norma Waterson or June Tabor do covers of non-folk / popular material, it is still perceived as being Folk by the general population, and by most folkies too.

To call Pop Songs 'Folk Songs' on account of the usual factors under discussion here (1954 etc.) is to miss the point of how Pop Songs are pretty complication creatures anyway, generated by communities and adopted and adapted thereafter according to a Master Idiom stretching back centuries and yet in a constant state of flux & renewal as new talent emerges to learn their chops, pay their dues & take it to the next stage as it suits them to do so. To call that process a 'Folk Process' or Pop Music a 'Folk Music' is to miss the point that all music is Traditional in that very sense. The very term 'Traditional Music', as I might have said earlier, is tautologous - Music by its very nature is Traditional, all music, but that sure as hell doesn't make it Folk. Folk didn't exist before the term was invented in the mid 19th century anyway; hell, even Prof Child thought of his Ballads as Pop Songs.

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Jim Carroll, on the other hand, knows what he's talking about. He's done some wonderful and important work, and has a great understanding of the subject. One of the few redeeming features of discussions like this is that Jim often shares his knowledge..

I doubt I'd bother if this wasn't the case.