It is professional to follow the FOM. If it says you don't have to wear a hat unless you have the coat on, that is being professional.

You wear the hat because you are scared of management. I don't wear the hat because its optional on our side, and it only becomes mandatory with the coat, which I haven't worn in over 10 years.

I either wear the summer uniform or the leather jacket, both are professional and in compliance with the FOM.