I believe that Graydon left Apple a while ago, but following compiler Twitter, it’s pretty clear that the rust folks and Swift folks are usually in good terms.
I would recommend @johnregehr, @shafikyaghmour and @trav_downs if you're new to the area. If you're particularly interested in rust, @myrrlyn, @ManishEarth and @steveklabnik are great follows. @jfbastien is a compiler dad-joker extraordinaire and @jckarter is a master shitposter (with a side of old Macs) if you're in need of compiler-oriented comic relief.
In particular, John tends to get involved in a lot of interesting conversations, so he's great to find more people to follow.