No, they're not saying that. They're saying if you want to market something as "broadband", it needs to be at least 25. They're perfectly free to sell you the 6 as long as they don't advertise it as "broadband".
That’ll hold for 6 months or maybe a year. Then you’ll be hearing from the FCC that your bandwidth is too low and you need to upgrade. It’s all part of the communist plot to take over the US. It was written into Federal Register by Congressman A. S. Herlong on January 10, 1963.
It is useless to resist. You really need 25.