From what I've seen, enemies will keep targeting a decoy drone even when there are 1000 missiles heading straight toward it. Each one ends up taking tremendous overkill (in some situations), so their effective health is very high. If I remember right, you can also down-power them, only switching a new one on when the previous one is destroyed.
Can Artillery Golems target these? If so, a cap of 9 should buy you 72 seconds to destroy the golem before it takes out your Advanced Factory / Fabricator / Home Command Station. I haven't tried it but presumably you could also use them to shut down a Cursed Golem for quite a while, given how long their ammo takes to traverse an entire planet.