No, it's not an agreement. Handing down a SCOTUS opinion is the most powerful thing they can do, and all lower courts are bound by it. But maintaining silence permits lower courts to continue operating each on its own best judgment. SCOTUS defers to the specialized authority of lower/local bodies all the time, saying, "We trust you have a better and more intimate perspective and will come to a good decision." That's not agreeing with a judgment call, that's letting somebody else make a judgment call, and being ok with the fact that SCOTUS may or may not have ruled differently.
* If the lower courts agree and SCOTUS leaves them to it, they are defacto supporting what the lower courts agreed on no? "We agree because we agree" and "We agree because we don't know but accept whatever you decided" are the same thing...
* If the lower courts do NOT agree (like this case), then by declining the case SCOTUS is... agreeing that the same law means different things in different places with their jurisdiction. Which seems even bad for a whole other set of additional reasons.
Still, here we are I guess. There are plenty of other issues that other parts of government refuse to address (and I would argue that there accept the default state of) so why not SCOTUS too...
Let's map the question to a different domain. Does a police officer concede that laws don't need to be followed, or that he is not bound to enforce laws, if he declines to pursue a violation of the law that he witnesses? Does he approve of the violation of the law by declining to pursue the matter? No, not at all. He simply can't pursue everything. But that he allows a thing to happen should in no way be considered an approval or agreement with the thing. This is a size-of-fish-to-fry situation.
