Wow, blue sky that's rough
Maybe use travel websites to find comparable cost hotels in the area and suggest them instead? Perhaps offer to pay the difference if he really feels strongly and it's not too much.
I know some companies don't give a hoot, they just want the lower rate and will insist. If they do insist, and if they're paying he's pretty stuck, tell him not to feel bad about it. It's not your money he's using so he isn't contributing himself. And he can still protest in his own way by not eating on property or using any paid services.