It's hard to really guarantee effectively without putting up serious money. The typical large closed-source codebase is full of undocumented things and hidden

It's hard to really guarantee effectively without putting up serious money. The typical large closed-source codebase is full of undocumented things and hidden dependencies on random chunks of proprietary environment. Making it usable as open source is a ton of work. And you can't guarantee that work will happen without putting up some kind of bond or buying insurance, given that the vendor could simply go bankrupt and not honor the contract.