Apple has either given a one-time exception or just changed the '2-letters or more' naming rule for the app store. A search for Twitter now shows "X" as your option.
Long ago, I worked for Cable and Wireless, a very large international telecom, that had just bought the assets of Exodus, a failed data center company, out of bankruptcy. The company held a "brand study" conducted by an outside consulting firm that was a giant rip-off, and somehow, the combined business became "Exodus: a Cable and Wireless Company." Leveraging a reputation for miserable mismanagement, and that of a bumbling global telecom. The business paid over one million dollars for that fantastic advice. Musk did this for free. Must be a genius.
Two days ago, Bleeping Computer reported that Apple had rejected Twitter's attempt to update its app name to simply X due to minimum character requirements. As a result, the app was temporarily listed in its App Store as Twitter—alongside the X logo and the X tagline "Blaze your glory." This potentially further confused users over what to call the app during Elon Musk's sloppy rollout of Twitter's new branding.
It stayed that way for days until about 2:30 this morning, when Apple updated the listing in its mobile App Store, Bleeping Computer reported—allowing the App Store's first single-character name. A product designer and data scientist who founded a growth consulting agency called Next, Nick Sheriff, posted a screenshot confirming that historically the App Store only accepted app names with a minimum of two characters.
Apple could not immediately be reached for comment on whether the exception was made exclusively for X or if a policy change might be coming that could benefit other apps with single-character names. On the desktop App Store, Twitter's old branding still appears as of this writing.