There is no way to prove that OpenCoin isn't "giving away" the majority of their XRP to addresses which actually are controlled by OpenCoin (or their employees) themselves. They would have to reveal the identities of the users behind those addresses for that, which is not going to happen as it would compromise the privacy of these users.
We drafted the XRP distribution plan. If we thought keeping 80% of the XRP was best, we would have decided to do that. I don't see any benefit to us doing it deceptively and, of course, there's significant risk to doing things that way.
You cannot possibly believe this to be true. You must think we're all idiots. There are 100 billion reasons for you guys to lie about the giveaways and zero risk of getting caught if you did.