Sounds like a pretty nazi-esque type of rule, but the employer sets the standard, and as long as they make that rule clear before hiring, it's up to the prospective employee to decide if it's worth it to comply.
More important than facial hair, or any similar picky rules, just keeping a generally tidy appearence important.
I really don't care if my guys want to grow mutton chops or a lincoln beard, as long as they keep it well trimmed and clean.
