I wonder if this kind of actions would bring or open something like a "precedent" for other situations
It wouldn't, it is clear to everyone who understands how BTC works that tx fees attached to a tx is for the miners, and in the case of an overpayment the miner has the right to keep their reward in fees or return it if they want to, whatever they decide to do is up to them and is 'right'.
Did you just say it's their right! Such right, Is it ideal? What's the ethical or moral philosophy behind that right in keeping what doesn't count as yours.
We understand that clarity about tx fees for miners but when you receive what's above your pay cheque especially to that range of amount of tx fees it will be reputable to return it to the owner as it could be an act of error, and no one is above error. One good turn deserves another. If that of 2016 mistake was returned then this should also be returned too.