Reading the analysis of Ricky Nelson’s “Garden Party” by Rico was interesting, and seems spot on in many ways. I would suggest a more plausible identity for “Mr. Hughes”.
If we take Mr. Hughes to be billionaire Howard Hughes, Nelson seems to be commenting on Bob Dylan’s having sold out by this time…possibly corrupted by wealth himself. He is no more than a semblance of himself…a billionaire wearing a Dylan disguise. This is more consistent with the justifiably critical remarks about the presumption of the audience (including John & Yoko, folks!) who only wanted to hear the saccharine teeny bop tunes and early rocknroll of the performers.
By the time of the referenced Madison Square Garden “party”, Nelson had matured and his look was more consistent with his then-current foray into country/folk-rock. The supposedly “open-minded” artists in the audience would rather see Chuck Berry in his Johnny Bojangles Goode costume and hear the old stuff the way they remembered it, rather than supporting their peers (such as Nelson) growing and maturing with the times.
It is a good song, about growing older, avoiding being pigeon-holed, and getting wiser. The very depth and deceptively soft delivery of the lyrics, complete with clear allusions and crisp, simple rhymes, seems to ironically prove Nelson’s point. I think Rico did a good job of answering the question and proposing a viable explanation, though I think association I’ve mentioned above is more literally and thematically consistent with the rest of the song.