Of course the federal courts can get involved. e.g. if a state made it illegal for a private citizen to own a gun, that would violate the US constitution. And that is the problem here with the lawsuit and why it cannot prevail. What the state did does NOT violate the US Constitution.
The federal courts are not bashful about "legislating from the bench" whether or not the issue at hand is subject to an interpretation of Constitutional principles. Over and above federal courts there are thousands upon thousands of bureaucrats, hidden away in a myriad of federal agencies (DOE, EPA, Dept of Commerce, &c. &c. ad nauseum) who spend their lifetimes grinding out regulations that have the power of law without ever being voted up or down by either federal or state legislatures. None of those are intended to make our lives more comfortable.
I hope you are right and their attempt at a lawsuit is tossed at first brush. However, I fear that an activist judge may well undertake a long and drawn out effort which will ultimately have to be heard by the USSC. The union tactic may be to play for a delay rather then an outright win.
Regards,
GtG