Won't the market pretty well extend the minimum wage? Not to disagree with the premise, but in Germany, for example, the union represents about 1/3 of workers, and whatever the union is able to negotiate basically becomes standard for all workers. Why? Because people will gravitate to those jobs with a protected floor.
If in 6 months wages in other sectors don't follow, then the workers will drain toward fast food and the other industries will have to be competitive.
But yes, I don't see why the law is discriminating here. Just raise the whole minimum wage.
The law discriminated because it was harder to pass a broad wage bill, and they are indeed expecting wages to follow fast food. This bill will do almost as much good, eventually, and was much more feasible to get made into law.
That said, there's no reason to not fight for a broader bill, now. Everyone deserves this as law, not just market consequences, even if those market consequences should result in a similar thing.