When the rescues I contacted were not willing and the behaviorist held out little hope, I realized that re homing him would be irresponsible. As much as I would rather he have a life than not, I want him to have a happy life and for people to be safe. This is not a 15 lb dog, nor is it a predictable problem, so the potential for damage and more bites to occur is way too high.
He is miserable being kept away from me for most of the day, every day. So his life is not and could not be happy no matter where he is.
This is not a decision I made lightly and when I pull back the emotion and think about it for what it is, I believe this is the best thing for him and for the people he may come into contact with. Even though it hurts like hell for me, it is the best thing.
I want to thank everyone on this forum for all the help, the suggestions, the support and the encouragement. When the time comes that I open myself up to another dog and that time will come, no doubt, it will be a Mastiff that I go searching for (even with his issues and the heart break, I have come to love the other qualities of this group of dogs) and I will return here to share stories and pick all your brain's some more.