Boss Tells Husband He Needs to be More Attractive, Or Else?

So my husband works a very strenuous manual labor job and all the men there are constantly covered in oil and grime. My husband is a fairly handsome man (in my mind he's a Greek god but let's be realistic here) and he has three outfits that he gets to wear to work that I wash every two days. As in, he wears and outfit for two days and then I wash it then he wears another for two days and so on and so forth. He usually has his hair in a half up ponytail/bun or a hat. He showers every night or if his eczema acts up that week every other night and maintains his long beard quite well (he puts more product in that thing to keep it silky than I do in my hair) and he always goes to work with a clean and washed face. He has decent hygiene and keeps up with his appearance basically. Well with us moving I've packed his other two work outfits and have just washed the same one outfit every night and he's been wearing that for about a week now. His boss approached him today and says, "You're a handsome young man. You need to start acting like it. Dress up and style your hair or I'll write you up. You need to be attractive for the customers when you walk through the shop." As women we have to deal with this everyday and you know how angry and belittled it can make you feel. Jake has no choice but to walk through the shop to get supplies and no other man there has been approached like this. He feels singled out and I was wondering if this was legal? It's one thing if you don't shower or something but he maintains his appearance. It makes no sense. I'm a little angry with his boss but I bit my tongue. How can my husband fix this? He can't wear his nice clothes to work or they'll be ruined. His boss needs to hold everyone to the same standards as Jake. What do you think? Was his boss right to do that?

The man jake is standing with is our realtor not his boss.