As long as the coin isn't a security, if Elon Musk want to create his own coin, he will definitely go for it. Who knows he his being the pseudonym founder of Shiba inu.
Cryptocurrency is unpredictable, when you think you have seen it all, just like yesterday when he tweeted some gibberish words that affected the whole market. I don't like him any more even when he said they have not sell Tesla bitcoin in their custody.
I do not think that he would be the creator of it, there is no chance. If he creates something he will create it and then tell everyone about it, he will not only tell it and tweet about it, he will definitely make a huge deal out of it as well, like send a toy of it to space or something because he is a very very crazy person without a doubt.
However one thing is for sure, he doesn't have enough time on his hands to be all hands on deck for a project like a crypto currency, which means he will have a whole team under him and he would have to deal with SEC so that his end is not like XRP or USDT and doesn't become illegal, which is why he needs to spend money which is not a problem for him, but a lot of manhours and effort away from his already amazing business' that he owns. Which is why I am not sure if he would do that, wouldn't make any sense (albeit he doesn't always do things that make sense.