I'd be fine with that. Best way would just be to report posts that do, so we can ask their creators to use the xcancel links, and remove them if they don't.

While I don't mind this, I barely see anyone posting twitter links here anyway, so it likely won't make much difference, even to us, let alone to twitter

Those usually get downvoted to hell anyways.

Not that I'm an .ml member but, thanks for considering this in the first place.