How about "it's an acceptable mitigation, but we want Boeing to suffer so we'll delay their new planes while letting the existing ones fly?" That seems to be the tact the FAA is taking and I think it's reasonable to take actions that deliberately punish Boeing and Boeing alone.

That being said, I'm also on the "this mitigation is ridiculous" camp. They can't even have a humidity sensor that turns the de-icer on and off?