[pook]

"I have no recourse because we split the venture 50/50 (no vesting). If I want to continue on the project without him, he can block it. I've tried buying him out and he insists he's committed and will not sell under any circumstance. My only recourse is to quit and block him from taking the idea and running with it. Neither of these are admirable outcomes and I'd rather run the business as far as it can go with a lazy co-founder than end it in such an ugly fashion."

I'm sure someone here would absolutely love to work with your "co-founder". Hell, they may even give him some common human dignity as well as an interesting project.