That's definately true. The problem is figuring out how to avoid situations like that without hesitating to speak up around people you don't know well.
I won't pretend to know the answer to that, but my personal approach would be to gather information about the people involved beforehand. If I can avoid as many surprises as possible going in, that puts me on (more) equal footing with the other players.
It sounds like the person you're talking about was using the conversation not as a way to acquire help, but rather to demonstrate that he didn't need it, probably in an effort to boost his own status in his social group. You're better off not working with that type of person.