But they won't do it unless they're asked.
The fact that they haven't spoken on the subject means nothing.
They may not do it until asked, but they certainly don’t have to wait until asked. You can keep saying that, but it won’t change the fact one bit.
The fact that they haven’t should shout to you they have no intention of declaring it unconstitutional. What the States are being required to implement, is probably undoable or at least would cost billions, so why do they not speak? I think they probably do not have the votes to undo this.