Much of the third world has very limited data thoughput or even much client side processing capability on their phones. "Not understanding" graphql is irrelevant. The key is to make as few requests and bytes transfered as possible. It seems the twitter mobile app hasn't been optimised for that, no matter what protocol it uses.
Is there a word or phrase which accurately describes the kind of erroneous fantasies and fallacy-ridden reasoning being exhibited by this individual?
The tweet linked by the OP doesn't dispute Musk's assertion, nor state why Musk "doesn't understand GraphQL"
Elon Musk DOES understand GraphQL, and why Twitter isn't an appropriate use case for it.
I've been amazed by the extent of the problems, but as for the fact that he doesn't know what he's doing ... well, this is the person who explicitly declined the opportunity to do the due diligence process on his $44bn purchase.