(Edit: removed silly comment about a personal interaction. The letter has also had addendums making the intent more clear. I will add "shut up on the internet" to the list of things I've learnt from the author)
I read this as, for want of a better word, snarky.
I'd bet if it wasn't Minix, L4 would have been on the cards. That's another microkernel that runs in coprocessors like your phone's radios that probably nobody will ever mention out loud.
Having been on both sides of the equation: imagine if a complete stranger acts like they are your friend, even though you've never met them, and offers nothing in the way of reciprocal ice breaking. Now repeat this dozens of times and bias it towards the socially inept and spergy.
The only thing that works from the celeb side is to power through and intently turn the conversation back onto the fan. But that requires genuine interest that you may not have the energy for, and it may not be what _they_ are there for either. There is a reason comic con actors charge for autographs: it's a very light weight form of prostitution.
Fans are genuinely annoying. They break every social rule, and come with a one way sense of familiarity only possible through modern technology, which our primate brain is poorly equipped for.
Don't have heroes. Don't put people on a pedestal. People have flaws, quirks, and failures. Admire good people for the good that they do, despite their flaws.
Snarky? Yeah, in a way. Honestly he just seems a little hurt that they didn't extend the courtesy of letting him know what they were going. But at the end he admits that he's the one who picked that license.
I read this as, for want of a better word, snarky.
I'd bet if it wasn't Minix, L4 would have been on the cards. That's another microkernel that runs in coprocessors like your phone's radios that probably nobody will ever mention out loud.