How does Treasury exercising the warrants violate property rights? Existing shares won't be taken away, they will just be worth less (as opposed to worthless).
I didn't see any hint in the RNC resolution that they would not exercise warrants. To me their bit about respecting shareholder rights means that the risk of our stocks going to zero is smaller than it had been. The government exercised their AIG warrants and it was not considered a taking after a court case and several appeals if I remember right. I don't see how these warrants are any different.