If you cannot see beyond your apparently still thriving Bush Derangement Syndrome, you need to seek professional help. No matter how you feel about President Bush, there is no excuse for HBO to have allowed this. Period. In fact, I hope the Secret Service investigates this, if for no other reason than to put those responsible for this through as much legal hell as possible. Threatening the President is a federal offense. I realize that this is not a threat as such, but it certainly is implied.
If you think this is cool because it was Bush, but you would have been outraged if it hade been Obama, or vice versa, you as well need to seek professional help.