It will undoubtedly affect the tourist trade. They are entitled to bring in whatever laws they want though as it is their country and not for us to tell them what to do.
Turkish Baths are a very civilised and long standing tradition from the muslim world. I annually enjoy my visit to the hot springs and mud baths in that country.
The Maldives interpretation is at odds with what has been practiced for centuries throughout the old Ottoman Empire. It provably won't affect the tourist industry too much. I don't think many travel all that way for a bath.
A friend of mine going on holiday in the Maldives took with him a bottle his favourite tipple as he thought that perhaps he wouldn't be able to get it there. He was right, he couldn't get it there because the customs confiscated his (un-islamic)bottle. He will certainly never go back.