I thought it was weird, allowing MC helmets. Until I read up on it and discovered, depending on the helmet, they are identical except for the fire rating. It makes sense to allow them in that case, with a head sock. Probably just to much trouble and a hassle for the tech inspectors to go through, easy just to disallow them all together.
I was always curios about what the main difference was, because I have two MC's and ride them a lot. Now I realize, I don't need to buy an MC helmet for "better or special head protection" on a MC, I could just use my auto helmet, same same.
