I'm not usually an "AI is going to kill us all" kind of person but on the off chance we do get Skynet/etc why would we give the machines the literal high ground?

I think it's less Skynet and more Wintermute: Some people saw the movie Elysium or read a summary of the book Neuromancer, and decided those were aspirational visions of how to be Untouchably Rich In Space.

Though there is a simpler explanation: Some guy with lots of stock in Rocket Launches and Datacenters has an extreme financial incentive to push stories where spending on both things simultaneously is the big new thing.

there has been a lot of pushback about building new data centers basically anywhere on earth might as well build them in space.

Because that's the next generation's problem, and we can do more to mortgage their future for our own luxury :)