I read an article on this. It's being introduced by I think a New York congressman concerned about the business his state does not get because all the Canadians use up their 6 months way down south all winter.
You have to be at least 55 and have some rental agreement or similar down in Snowbird country. I think an RV pad would meet the requirement from what I read.
There was also some subtle mention about a tax implication being ignored in the bill for this country (US). Don't know what that's all about.
I've always been puzzled why a Canadian can't come down here for as long as they want to Snowbird but then there is a lot about Washington that puzzles me.
Globe & Mail article with pretty good coverage of the subject.