But it wasn't a UAW event. It was the Electric Vehicle Summit.
Not that it matters anymore as Trump undid all of that, so there's no longer a pledge to switch to EVs, nor is there any sort of federal tax credit for purchasing EVs (technically there still is, but only until September).
I'm sure this is a much better deal for Musk overall than not being invited to an event.
What led you to belive it wasnt about the UAW? just the name of the event?