That wouldn't be useful against quantum-radar (i.e. radar that uses quantum superposition as an identity tag, the moment you fiddle with the radar return, it'll show up as fiddled with by the radar set) if what I've read about Q-Radar is to believed.
It depends what you're actually doing with the signal. Quantum radar could theoretically protect against broadcasting a spoofed return, but other EW techniques would potentially still work and it will undoubtedly open up new EW techniques. And a viable quantum radar faces major technological issues - the need to compare the return signal with a reference copy split off it as part of the signal generation process - that gets worse the longer its range is (because of the increasing number of signals you need to hold in some form of memory without altering their quantum state).
And of course this is an issue for all EW systems, not simply SPEAR EW.