Ah no. Directional GPS jamming is quite effective with an easily sourced satellite TV dish, a tripod and some straight forward electronics. You can even point it at a plane using their own ADS-B signal.

PPDs are omnidirectional, but quite hard to precisely geolocate when intermittent and moving, as was the case in the well known Newark events (which shut down a major airport).

Airports with difficult approach (like the old Kai Tak in HK) could easily result in CFIT with only small errors, let alone other aircraft.