WIY: I read that article (or most of it). I don’t know who R’ Hochman is, but what he did to the T’shuvah of R’ Tzemach Gaon is just, well, I’ll let you re-read it and decide for yourself. It’s not P’shat.
That being said, I don’t think anyone (aside from R’ Tzemach Gaon) ever took Eldad Hadani seriously. He was respected as an Aggadic authority and Talmid Chacham (and therefore quoted by the Rishonim), but I don’t think the vast majority of them actually believed that the travels were real. They were all a Mashal for couching his Aggadah and Halachah.