It's not an impossible position if you have the balls to say, "I'm sorry, but I'm uncomfortable with your dog in the shelter." Not my problem if you don't. Your assertion that it is rude to even ask is ridiculous. If I ask and everyone enthusiastically says, sure, no problem, then there's no problem. If you don't have the guts to say there is, that is YOUR problem, not mine.
"he's just looking out for your safety, but maybe you know better and should just go for it"
He's looking out for my safety by being a pompous, arrogant jerk who behaves as though he's written the be-all, end-all book on "hiking etiquette" and how to be a "woodsy type?" Please.
I'd rather spend a night ina shelter with a dog than with a psycho homeless dude who talks to himself and has been living out of the shelter for more than a week. But that's just me.
Again - if you don't have the self-confidence or self-assuredness to speak up for yourself when you're put in a situation that makes you uncomfortable, that is your problem. I don't ask if it's okay because I know that it's not - I ask because it's the polite thing to do. I'd strongly disagree with whatever ignorant statement someone made asserting that most people are uncomfortable with dogs in shelters. I've met people in shelters who are way dirtier, smellier and nastier than most dogs.
It's like any other situation - if someone is smoking pot or doing drugs ina shelter, you can ask them to stop or you can leave. If there is a psycho homeless dude in a shelter, you can ask them to leave or you can leave. If there is a pleasant, calm, quiet dog in a shelter than curls up on a blanket and passes out and does not bother a single person, and the owner asks you if it's okay if the dog sleeps there in the corner... you can either say no, i'm not okay with it, or you can leave. There's no law saying a dog can't be in a shelter.