Quote Originally Posted by CDNSushi View Post
Although approaching HR might clarify whether kilt wearing is indeed against company policy or not, it will do little (read: nothing) to alleviate the situation locally. If the manager is convinced that it is "unprofessional" then no one in HR will tell him otherwise, even if it IS technically allowed. If you pursue this issue, I can virtually guarantee that there will be some hard feelings from being proven wrong, and he will go out of his way to find OTHER grounds for negative performance reviews, transfer, dismissal, or whatever it will take to get you out of his hair.

Remember the old adage: A mind changed against its will, is of the same opinion still.

The best advice I've seen here thus far is to indeed evaluate where kilt-wearing stands in your list of priorities compared to the job you currently have.
I've been trying his to compose this exact sentiment...well said CDNSushi.