I would simply make it so the character doesn't want to cast the spell anymore and is incapable of wanting such thing.

Yeah, they could cast it if they willed it. They don't will it. They can't will it. So they don't cast it.

And yes, if they ever got hold of level 9 spells and picked meteor swarm, they wouldn't be able to cast it that way either. They used a wish spell to guarantee that their stupidity be punished, and so it shall.

And before I get heat for being "no fun" with such a response, consider this: if the DM let that happen, the game wouldn't be fun for anyone anymore. The guy who made the wish would be godly and so get bored out of sheer lack of challenge. All the other PCs would be useless and not have fun. The DM wouldn't be able to throw any problems at the PCs because the party can just rain meteors on it.

So you're putting the DM in the position of either saying no in any number of ways or ruining the campaign because you couldn't be bothered to either be sensible or read what the Wish spell does. Nobody gets out of it looking good because you had to be dumb, so fuck you, no Meteor Swarm for this campaign under any circumstance, and the Wish spell is used and triggers the backlash as well.

I can understand "I want to be immortal" or "I want to cast this level 9 spell once". That can even be arranged without too much backlash and can develop in fun ways. Suddenly you're a vampire or you have a Timestop scroll or whatever, it's ok. "I want to cast Meteor Swarm at will" is just such a specific flavour of idiocy that it deserves punishment without even the effort of ironic mockery.