And just to pile on a bit...
3-5-3e Exception a, of course, follows hard on the heels of 3-5-3e which quite clearly prohibits the device in question: "Head decorations and headwear, except those specified above, are prohibited."
To call it a guard would be a
generalization, at best. But 3-5-3e
specifically disallows all headwear not enumerated in 3-5-3a - 3-5-3d. The specific prohibition trumps any more general ... hibition? So to be legal, it would have to be individually permitted by the state association per Exception a.
I would not presume to constrain what the state association may choose to allow, especially if it is for medical reasons, but... Exception a specifically addresses
a covering or wrap for the head. This contraption is neither.
:shrug: