I think the real solution is he wants money. If it was solely to reduce spam/bot activities, then there are other ways to do that. Maybe a Bitcoin-style proof of work scheme where evey post needs to show a hash of the message with a nonce. The difficulty needn't be that hard to make mass posting computaionally unfeasible.

In fact, Bitcoin appropriated this proposal to reduce email spam. It never took off with email as it was an open system and network effects and a catch 22 meant that it floundered. But X, née twitter is a closed off dictatorship. They could force it through edict.