This news already been talked 2 months ago, look at his tweet.
He only want to get paid when he become mayor, this means if he doesn't become a mayor he wouldn't want to get paid in Bitcoin. This is just his strategy to get voted by Bitcoin enthusiasts, in the end it's just for politic not his own desire. If he really want to get paid in Bitcoin, he can just buy Bitcoin with his paychecks... there's nothing different.
He is the elected mayor already in NY which he said to buy BTC with his salary. He also said earlier that he has not gotten his pay yet as NY mayor. AS the Maimi Mayor also calls out all the mayors in the country to join the crypto compact in buying BTC. It's kinda pact of mayors to buy BTC and convert all cities to adopt BTC.
But it could be true today that politicians will be using Bitcoin to get votes from the people. Though unconventional, BTC is a political tool today.