When you say he 'partially financed' a deal...do you mean he did do so with his own money, or did he use borrowed money?
If the former, then (w/o knowing what his exact responsibilities/type of agreements made actually were) 'twould appear to be a "no harm no foul" situation as you suggest. But, if the latter - he 'stuck' someone else with his debt by "walking away". (An example of the latter would be if he ordered/received items from suppliers, 'cash flow from the property deal dried up, so he walked away from the supply bill.)
What I'm saying is, anytime someone takes on debt, it's his responsibility to service it. One does not just walk away and leave it for some other party to deal with/absorb.