If they build it, they have to be ready to use it. And they'd have to use it pretty close to home. Against an adversary with equal capabilities.
Either it would have no effect at all on the conflict, or it would result in annihilation. Doesn't really seem worth it.
Though maybe to play devils advocate, creating a DMZ wasteland with tactical nukes might not be the worst outcome. Pretty terrible thought though.
Maybe don't base your world view on some random person's protest sign.