The ruling is a restraint on goverment, period, at every level.
What compelling reason does government have to regulate the sexual activities between consenting adults in the privacy of their own home?
I see you've boughten the myth that this is about privacy in someone's own home. It's not. The decision did not address the police or government's ability to enter or search your property. The government/police have the exact same power now as before.
This ruling protects gay sex wherever it is: home, public park, public bathroom, parking lot, alleyway, etc. It is not just what goes on in a home. Do you think that this ruling will make more or less likely that a local government will try to prevent homosexuals from turning public places into their new bedrooms?
You ask what business is it of the government? Perhaps the real question should be who decides? A handful of unelected officials in washington who won't have to live with the results of their decision. Or by the people who live in the city or state through their elected representative. the People who will have to live with the results, and the representatives who could be voted out if the people don't like the results. Which way do think will advance freedom most?