Thing is EITS, submarines don't drag a signal-jaming buoy behind them, or release them along the way as they proceed somewhere. In both instances, that would be leading the predator to the prey.
And they wouldn't do it as they detect an airplane either, if they ever do manage to spot a Poseidon at that altitude.
Much more probability of using counters to evade the torp once it is in the water than to try and fool the drop guidance system.