Hey flaps - been down this road before or one similar if I remember rightly.
Captain is in charge - it's in the books for all to see so if anyone thinks different, go read up.
I think there are a few "grey areas" that could be sorted out, but 99% of captains I've met are happy to leave what goes on in the cabin to the cabin crew, and in the same way the cabin crew don't decide if we need deicing or not.
But when it comes to safety issues and emergency proceedures they are set in stone and must be followed to the letter.