It's not new. You've got mandatory flood insurance from a selected group of companies, mandatory osha safety training from a selected group of companies, mandated accounting procedures that must be certified by selected people...
If you disagree with the law on principle, that's fine, it's certainly not a perfect solution.
But those are political objections. Based on how the interstate commerce clause has been interpreted for a wide variety of issues, it's not unconstitutional (for most working definitions of constitutional). That's why Pelosi laughed and moved on to the next question.