If the rock and seat belt incident had happened before you would expect RGJ to be saying as much as it would make them look less culpable so it stands to reason it happened after.
It also stands to reason that they do not know, and no other papers have been able to confirm it that I could find.
I'd expect it to make the most legal sense for Tesla to avoid posting this, if it is in fact true, until the case has been prosecuted. (I am not a lawyer.)
While I like Tesla, it seems like one of those situations where it is best to take a statement like this with a grain of salt until more information is released by a party other than Tesla.
I do find it surprising that most people here aren't more skeptical since it feels like something is missing.
It's at least partly because Tesla has built up a reputation for being pretty honest and accurate, and not wildly misrepresenting the facts. Tesla has a lot more to lose here than the RGJ, boldly making false accusations seems like the kind of thing that would turn a minor blip into a PR disaster, and that's not really their style (but of course that's just speculation).
I would expect the RGJ to defend themselves and their guy a bit more, if they had reason to (since the Tesla post is pretty damning), but perhaps they are waiting for more information. Time will tell.