So, why do Jehovah's Witnesses always answer questions through the bible?
It's what they claim they base all their believes on. They aren't the only religion who believe that everything they preach comes from the bible.
It doesn't at all, however. They have gazillions of publications and meeting to discuss and interpret the bible, hence, it's merely interpretations like other religion that uses the bible as their official guide.
... I'm trying to get people (the friend stated above is one of them) I know who are JWs that their religion is surely not what it seems to be.
First, why on Earth do you want to intervene in people's private life decisions without their permission to change their religious believes? What exactly is your intention? And who are you to get into people's matters like that?
I can't care less about the WT and their believes, but that doesn't entitle me to intervene in other people's decisions.
Furthermore, the first thing you should know about your friends, before anything related to doctrine and the bible is WHY DID THEY JOIN? You don't think that they entered that organization knowing all that bible nonsense, right? Then there have to be reasons for them to join. That's what you should look for if you have a real interest in their well being.
Good friends love their friends unconditionally and respect boundaries and their decisions, and love them anyway. Just sayin'.