Why not just rivit or zip tie it so that it doesn't rub?

And, honestly, why have a fancy rear brake line anyway? If you're using the rear brake anywhere near hard enough to need it, you're doing something wrong IMHO.

I'd consider taking my rear brake off if the rules allowed it, it's just ballast as far as I'm concerned...unless the front brakes fail, which is why they don't let you remove it!