I think the best that could be expected in that case would be for such a weapon to miss its target. It would be very nearly impossible to send out multiple time markers for the purpose of substituting a current fix. Coordinated microsecond precision between multiple markers would be needed to spoof any fix, especially since the position of the target being spoofed would have to be known to within a meter. Besides, the timer markers, ephimeris/almanac data for the military is seriously encrypted and transmitted with spread spectrum techniques.
I don't think GPS can be hacked. It could certainly be jammed.
Unless the [Chinese made COTS] GPS chips themselves were boogered to take valid GPS data and report an offset position only when certain conditions were met.
Approach a given endpoint at a certain velocity and the chip subtly offsets the reported position to cause a miss, for example.