There is a lot of mythology about gods walking among men, hiding their true nature, etc. And more recent examples include the TV show Lucifer.
Someone wanting to roleplay that sort of being is entirely plausible. Without knowing the person's personality (which you presumably did) it's hard to say whether they would have genuinely wanted to do that or if it was an excuse.
(That said, another approach is to have a conversation about "what are you trying to achieve", and find a way for everyone to have the fun they'd like to have without risking something game-breaking.)
To make it clearer, the players and the GM will be struggling against each - in a controlled way, yes, but also a meaningful way. I'm not a super deadly GM but players will be risking death in at least low-key way and so everyone will sooner or later be "using everything they have".
Edit: basically, saying "this rule/power/etc exists but won't have an impact" is more or less saying that the "rules aren't serious", in either the 'Chat Control' or the DM situation. But the very nature of rules is that we wouldn't have them if they weren't serious.
If you're playing an off-the-shelf campaign this is problematic. If the GM is creating the game as you go, then a good GM should be able work with the player to make this reasonable. The GM can always use GM-power to prevent a player from doing something, even if it involves a literal hand of God reaching down to stop them.
A conversation with the player beforehand to make sure you're on the same page about this sort of thing would go a long way. Let them know under what circumstances you're willing to allow them to use whatever the power is. Let them know the consequences if they don't follow those rules.
Unlike with ChatControl, a D&D game is a situation where the necessary trust is able to exist.
An example: agree the player character is some trickster djinn sent from another plane to learn to be a human and how to trick people. They have immense cosmic powers of life and death, but as part of being sent over, they can only use the power for immediate comedy. Violations result in the djinn getting yanked back to their plane and disincorporated.
Boom done. Now you have a massively OP character that can only use their power in humorous situations that don't affect the storyline, and if they try to abuse that then that's instant-death.
I've played in games with "the GM kills you" mechanics and it felt juvenile/arbitrary/abusive. Remember, this is a game where every players' character needs to "shine" and similarly needs to know they're being judged with fairness and compassion by the GM (compassion especially along the lines of "understand what I say my character does as something reasonable").
A player that in good faith wanted to role play such a character, would work with the DM in advance to structure rules well-understood by all parties about exactly what would happen if they abuse their situation.
All the DnD situations can be trivially resolved by good-faith and communication on all sides.
Unlike Chat Control, where good faith cannot be assumed.
D&D is intentionally a collaborative story, and it shouldn't be out of the question for players to collaborate with the DM. Focusing on "the balance between player and GM" is great for a dungeon-crawl style game (which I would argue is the only thing 5e is actually designed for, and is poor for what most people try to use it for, but that's a whole other rant), but putting too much focus on it in a more roleplay-centered campaign can lead to a very adversarial relationship between players and the DM. If you have great players, you should trust them to collaborate with you, not just opposed to you.
But I don't think this really relates to "my character has excess-or-god-like powers but I won't use them" situation. The point isn't the characters can't have more free-form powers that GM interprets sympathetically. The point is if the player has to say their character has special over-the-top-powers, they are creating a rule, not leaving things for free collaboration. I remember in a FATE game in which one player specified has character's aspect that "world's greatest thief" and this both abuse of the FATE system and actual harassment/psychological abuse of another players. I learned the lesson that aspects never should superlatives to them.
For starters the government is not in the habit of releasing these new powers, once it's established it will stay for a very, very long time.
And you can be sure the new powers will be used in unintended ways, which the citizens will have a hard time blocking.
So it's actually very simple: No to Chatcontrol, now and forever.
If promises about licenses meant a damn, we wouldn’t have speeding cameras.
(Technically correct is the best kind of correct)
[1] https://www.drivencarguide.co.nz/news/no-charges-laid-on-bug...
In contrast, an expensive speedy car disguised as a cheap slow one would be much more suspicious.