It's all up to you and your team-mates to decide what the "right thing" to do is here, but thanks for bringing your concerns to the village square. I'm sure that you're not the only one with doubts on this topic. Some contests are hard to take at face value, and it's unfortunate - but just - that opaque incentives and unclear conditions are giving hackathons a bad rep. A great way to fight back to this would be to take your winnings, donate them to causes that you feel are wholeheartedly backing grassroots efforts to support Open Source development. Then share your story, and keep up the good hacking!