Yeah, but he doesn't do that. Like, his use isn't even restricted to nouns.
There's also a rare use in English where someone treats a non-proper noun as a proper noun to imply that they have entity-like status. I don't know if there's a term for that. Like, oh...
"Jim made sure to leave the toilet seat down. He knew that for Anne, this was one of the Important Marriage Obligations that he had."
But he's not doing that either, though that's the closest thing I can think of.
At one point, he stated on Twitter that he did it for emphasis.
He also does all-caps words, as well as capitalized words. The former is a conventional way of showing emphasis.