Jamming them is easy, replaying them so as to trick unacquainted receivers is easy, but "faking" a network of signals so as to precisely control present a specific location is not easy or feasible.
"Overpowering" (as to jam) inherently means detectable, these signals are arriving below the noise floor anyway. And if you aren't overpowering, the original signals will leak through. Also, depending on the sophistication of the receiver, your ability to present an implausibly different location may not exist at all (AGPS.)
Yes, a motivated actor can move a naive receiver somewhere different than where it thinks it is by some small amount - ideally outside of the CEP of whatever weapons system is targeting, but that's much different than precisely controlling the location to be somewhere else arbitrarily.
