ethical question re business ethics (naked coworker)

let's suppose you are away on a business trip for your company at a trade show with many other employees from your company.

at the end of a grueling day, several of you plan to meet up for dinner, and one of your co-workers suggests that you drop by his hotel room to get him before you go.

so you do. he answer the door in a towel, saying he's almost ready, you can wait. you sit in one of the arm chairs, he goes back into the bathroom (shuts door) to finish dressing. you pick up a magazine to read it.

he comes out of the bathroom buck naked. you bury your face into your magazine, very uncomfortable.

he says this is normal in his culture. you say you are uncomfortable.

he doesn't come on to you in any way, but he parades around the hotel room naked.

you make a beeline for the door and make regrets about not being able to go to dinner.

do you report this to your company? what if it happened 4 years ago? assume you both still work there, and you are concerned he does this to other employees. also note that he is moving up in ranks around the company. also note that he has been in our country for MANY MANY years and is VERY familliar with our culture and what is deemed appropriate or not appropriate, regardless of what is appropriate in his culture.