Sure, depending on the environment. But when an aircraft is in one of those environments where reflections and line of sight to satellites are an issue, GPS accuracy is the least of your concerns.

This is in regards to an emergency response system, so an attacker would have to wait for an emergency to attack and well, you may as well just see how it pans out naturally rather than risk jail time to try and coerce an accident that might already be happening.

It’s not (just) about attack though. If you have your emergency in a place where the surrounds cause GPS to be inaccurate you cannot rely on GPS. Ergo since you cannot plan where to have an emergency relying on GPS is not sufficient.

I don't believe LoS blocking is really an issue as you approach an airport runway from above...

If you can make sure you only have emergencies when near an airport then you've already solved a lot of the hard problems.