I’m familiar with thither from the phrase “hither and thither”, which is a stupid-sounding phrase I read as a kid, and why I remember it. (Similar to knowing what “yon” means from “hither and yon(der)”)

I wouldn’t ever use either word, because I don’t see a need for pretentious pomposity, but perhaps he does. :)

I did used to have a friend who would use words correctly, but obscurely, and while he was smart and just enjoyed flexing his vocab, it was obnoxious af for everyone around him because even someone on the same intellectual level is going to go “what…??” Like, a lot… (basically, it is literally impossible for two people to know all the same things, so it’s just a “look I’m smart!” Flex). It’s just a bad way to communicate. Good way to be a poet, though.