Court lacks jurisdiction? No remedy?
Are they serious with that crap?
This case is going to be heard on the merits, and it's going to be heard by the Supremes, eventually. They won't be able to escape that.
If it's a tax (big if), the Anti-Injunction Act says that no court has jurisdiction to enjoin the collection of any tax. There is, however, another remedy, which is to pay the tax, ask for a refund, and then sue in the Court of Federal Claims.