It doesn't work that way. If the missiles are already targeting your ship, and your ship is visible on enemy active sensors, there is no way to knock them off course, except, perhaps, to destroy the ship with active sensors that your ship sees.
Nothing else but destroying your ship can affect the flight of the missiles.
Now, if missiles with sensors did not stop moving after the loss of the target, but continued it - then yes, then there would be a point in such things ... but if desired, it is so easy to implement.
Active sensors will target the largest ship: this opens up opportunities for deception: simply create a huge armored commercial ship with a bunch of CIWS.
I'm not sure if the AI uses heat, but if it does, you can keep 1 huge ship with very powerful engines in the fleet. And if the most powerful active scanners are put there, there will also be deception of EM missiles.
In any case, taking into account the level of intelligence of the AI, all this does not make sense, because it is enough to create sufficiently long-range missiles, and it will be possible not to think about protection at all.
