One of the best proposal I have seen in recent times to end the consensus controversy. Have you tried to post it in the bitcoin-dev mailing list?
bitcoin-dev mailing list owner asked me to post it in bitcoin-discuss mailing list first. So, it is there -
http://lists.linuxfoundation.org/pipermail/bitcoin-discuss/2016-February/000080.html.
So how exactly is this constitution suppose to be enforced?
Why would anyone obey it?
Neither it needs to be enforced, nor anyone needs to obey it. It'll do good as an unofficially defined process for consensus resolution. And once, a hard fork proposal passes through the process stated in this constitution, it'll have the majority of hash power with majority of coins backing it. The majority of hash power with the backing of the majority coins is what makes the longest chain ticking in bitcoin ecosystem. Everyone else 'obeys' it.