This is very odd. I can't see Ford just randomly showing up to GM's turf and being let in like that. It could be possible that they're collaborating on something, heck everyone seems to be doing it these days.
There are a lot of unanswered questions that's for sure hahaMaybe, but the article also says that they reached out to Ford and they "got a very clear “no” from Ford Global EV Communications Manager, Emma Bergg". Who knows if they're lying or not.