I know it sucks...the guy wants to volunteer his skills (and that's more than most), but the meaning behind the grooming standard is much more than what is on the surface. Camaraderie and being part of a team account for a lot.
For example, I work with black, white, brown, yellow people...we all wear the same uniform, same standards and have the same big picture military goals...regardless of branch, rank, whatever. I go to a civilian event with those same people, and they're dressed in their civilian clothes. Gold chains, combs in their hair, baggy pants, wife beaters, whatever! Hate to say it, but I judge them even though I may know their straight laced military persona.
Religious garb has no place in uniform...as a Catholic (albeit a recovering one), I'm not allowed to display a cross around my neck on the outside of my shirt. Ignoring the huge chem-bio weapons issue, how is a beard and turban different?
Active duty in uniform? Shave your face and cut your hair. It's the reg..cut and dry (pun not intended). It's not my place to question it. If DOD sees fit to change it, then I'll enforce that.
Ed