Elon had X.com for ages. He had before they merged with Confinity to form PayPal, Inc. He wanted PayPal to be renamed to X.com back then, but PayPal had way better brand recognition, so (even though he was CEO) internal backlash talked him out of the idea.
The former Dutch brand Xs4all (ISP) had a marketing campaign where they asked input from their customers. It evolved around the X. It taught me X stands for a lot of things. It's a letter, for one. It's a cross. A railroad crossing. It's a knot. It also stands for trans (in the broad sense of the word, including but not limited to transsexual). There's also an association with masculinity.
That X stands for so much isn't coincidence. Musk wants you to think of his brand (X.com; not X) when you see the letter X, or even subliminal in the examples I gave above. My take is it could work out on the long term, but on the short term it further alienates Twitter's status quo. It could accelerate the domino effect.