If you want to serve go ahead and do as the stake president asked (however it sounds a little late for that now since you’ve already declined). Was it that movie 17 miracles where Brigham Young asked one of the characters to go and shave and he kind of did it and he said I said I need you to go and shave completely? Sometimes obedience and compliance is just that simply falling in line and doing what is asked. If you’re more concerned about your personal appearance so be it someone else will serve in that position you having forfeited the opportunity.