That's for standalone servers. xAI has something that nobody else has. The single largest interconnected cluster[1]. For inference it doesn't really matter, but for training that networking is crucial.

[1] Probably, there could be undisclosed clusters owned by other companies.

I would think that for training Google has optimized their entire setup for TPUs so I can’t see how this would be used for anything but inference

That's a good point. That makes it less likely that it's training, but who knows.