My understanding of GPS spoofing is that it affects all receivers equally, and is not targeted to a particular receiver. You couldn't (easily) guide a particular westbound aircraft 1,000 ft lower into an eastbound aircraft on the same airway, opposite direction, without the eastbound aircraft also being the same 1,000 ft. lower. To say nothing of sanity check with baro. alt.
Even in lateral navigation, where there is not the same kind of ready redundancy, likewise if you spoofed a signal 2 miles east, every receiver affected would be the same 2 mi east. It's like ATC vectors being heading-based not track-based -- we're all swimming in the same pool.