What are you transacting? Ultimately, you're going to be transacting in a real world "thing", rather than just something on the chain. So you haven't actually solved anything, there is still a layer of trust involved. You still rely on your enemy to either make the transaction after you deliver the "thing", or you rely on your enemy to deliver the "thing" after you make the transaction.
Sure, you can stand there with guns to heads, but then you could just do it in cash, no need for bitcoin.