I don't really understand why he'd say he'd cover the costs personally... like, Vercel can just write it off, what's the significance of him paying for it?

Personal brand building? Wanting Vercel to stay out of politics? A vague attempt at diffusing the focus on Vercel pricing?

Really hard to tell.

Assuming that he wants to keep Vercel out of politics is a somewhat wild take considering what he’s posted in the past.