If you build a cage , my biggest piece of advice would be to make it so he can look out a window. They love looking out doors so much, staring at walls must be torture.
we did this by building a small room inside of a larger room but we have also built cages in the past and just cut a hole in the back and used mesh screen then placed it up against a window.
you have to ask yourself if you could truly find someone else that would put up with him if he behaved that way. not many people would which could lead to a life of abuse or being passed around to many owners.
theres also the chance he may snap out of it or may be sick which can make them act aggressive.
Heres my story of my big green grumpy iguana. He passed almost 2 yrs ago from stomach cancer but seemed quite happy without us prior to that.