That already happened with the merger of X with XAI and then the merger of Xai and SpaceX.
But the reason is because SpaceX is trying to tool up for orbital datacenters. They're building a bunch of solar cell manufacturing plants and Starship launch pads.
It didn't already happen. As you pointed out, people who funded the purchase of Twitter hold SpaceX shares, and this IPO is how they get their money back.
Orbital datacenters is just an excuse of a reason to merge the two companies when there’s nothing else tying them together. They won’t actually happen.
Or at least they are selling the idea of orbital data centers since the technology for orbital data centers does not exist yet or in the short term.