I assume he's reviving a new drive at internal consolidation and reviving the internal efficiency of X. This would be a good start considering this CEO's track record so far. She served a certain purpose and it's workable to replace her.
As for Musk's ownership of X itself, and his buying it: If I had been in his shoes, i'd have tried to squeeze for a lower price maybe, but the company was a worthwhile acquisition and the future is too long, with too many complex turns for anyone to clearly say whether his ownership of it is a business failure or a long-view piece of wisdom. What he controls now is still relevant, and if certain political/social winds change, could be more relevant still down the road. In either case, it could easily be a valuable political and business tool for Musk himself, for many years to come.
I simply don't see the destructiveness and failure that many people, here on this site and elsewhere have ranted about with Musk buying Twitter. Even with the firings and brand change, well, how necessary did those staffers end up being? Not much as it turns out. Better to have gotten rid of them during the initial chaos of a handover, when you can in any case expect problems from all corners, and then work on rebuilding with a fresh and company-aligned base that works to ensure stability down the road.
Being the richest man in the world, and one who has already assembled two consecutive historically noteworthy companies (Tesla and SpaceX), Musk is certainly not stupid even if his personality can be grotesque at times, some of the comments here claiming otherwise have no rational fucking clue what they're talking about. They speak from emotion, perhaps driven by ideological fixation, but not based on the visible evidence over multiple decades.