I've also posted on the topic in other threads, not that I expect you to search my entire history.
Elon can run 5 companies but they will all suffer. I'd prefer Elon's brain to be more focused on Tesla and SpaceX primarily, Boring and Neuralink secondarily, and Twitter not at all, obviously. I understand that Elon sees Twitter as more than just a social media site, I disagree with the importance of owning twitter to achieve his goals. Obviously at some point in this endeavor Elon agreed with me and tried to get out of the deal. Now he seems to feel his hand has been forced because his case was weak. He'll do what he can to make the best of this mess he created, to the detriment of his other companies and with no guarantee of success. I also think it likely he'll make Twitter worse overall in the long run but yes it's possible I'm wrong about that.
There's a bunch of sentences strung together for you.
As for Elon and Tesla, he isn't involved to any significant degree in the routine running of the company. He is closely involved in some of the R&D projects, like FSD, DOJO, Optimus SubPrime, etc. I suspect this is mostly on an advisory and supervisory scale with the people doing the heavy lifting on-site, rather than directly working on the projects himself.
SpaceX is his biggest focus. This is where he does significant hands-on work on the Starship project. Closely monitoring for ways to further streamline the production and development.
Boring and Neuralink seem to be self-supporting. Elon's involvement is similar as with Tesla. Checking in periodically and offering guidance when necessary.
What little it will take Elon to initially assemble his Twitter team is a valid up-front time cost. A few months down the road his involvement will be mostly in an advisory and supervisory capacity over the R&D projects there as well, working with the teams tasked with achieving his goals. Granted, there is the chance for occasional moments needing immediate attention by him along the way, but, compared with getting a production line running for Tesla or SpaceX, transforming Twitter will add no significant burden upon his resources.
Elon has demonstrated for most of his adult life how this method of juggling projects is exactly where he performs at his best. Once he has sorted out the key management and operations staffing it seems unlikely Twitter will make any call upon his attention that would have a measurable effect on the operation of any of the other companies.
Professed fears over this do not seem to be so much rooted in an analysis of Elon's success in employing his method of operation as much as they may be more about us Muggles trying to imagine how any one of us might do it.
I trust Elon to know his limits better than I would, and to achieve his goals at whatever pace he finds comfortable, as he has done up till now.