“the ability to recover that signal is a function of signal to noise...you can not pull the signal out.”
That isn’t true at all. Selectivity and signal processing is of prime importance with signals in the noise. Your knowledge is obviously with CW type signals and the rules change with these jam-proof signals.
No, I am intimately involved in GPS receiver design and performance. You can believe what you want, but any receiver can be jammed with sufficient power. GPS being spread sprectrum has ‘some’ protection from that, but put enough noise power on the receiver and it will not function.