Considering the fact that Fox's safest oos option is probably shine, having his back turned doesn't hinder him much.
If Fox A were facing towards Fox B, the only thing he'd accrue would be his shield grab. Mind you, the bair would be lost but it isn't that big of a sacrifice assuming you know how amazing usmash oos and shine oos are anyways. For most characters I would agree, having your back turned in shield is bad. But Fox/Falco players don't have to worry about it that much.
My theory smash scenario:
Fox A is in shield, facing away from Fox B
Fox B waits for something so he can CC it and be smart and stuff
Fox A jump cancels a shine perfectly out of shield
Shine hits the CC'ing' Fox B
Fox A turns around and JC grabs
c-c-c combo
(this shouldn't work btw)
also, when you have techskill your Fox should be able to do amazing things like this:
http://www.youtube.com/watch?v=dr1mhUPsCWc&feature=channel