The fact that St Michael's Mount is on this line is enough to show that it is nonsense. It's an unbelievably lovely place and it was a site for pilgrims, but its ecclesiastical connection to St Michael is relatively weedy; a brief period of time.
It's far more interesting to me that Perkin Warbeck occupied it!
Yup... actually the linked Wikipedia page doesn't use the word "cathedrals", but they are remarkable in other ways (long history, pilgrimage sites etc.). Ok, Skellig Michael is now remembered mainly for being Luke Skywalker's island in Star Wars VII/VIII, but still...
It annoyed me as soon as it appeared at the tail end of TLJ. I've wanted to visit it for a long time, but it's a bit of a hassle to get to. I can only imagine that it's even harder now that it's a pilgrimage site for Star Wars fans, and not just rock-botherers like myself.
It's far more interesting to me that Perkin Warbeck occupied it!