By that reasoning, he’s entitled to get whatever he asks for in exchange, which implies that, if he gets less than that, his rights have been violated. But you’ve already disagreed with that notion.
I think it’s justified on the basis of “common purpose” (also known as “joint enterprise”). Think of a bank robbery. The person driving the getaway car may not have violated anyone’s rights, if he stayed in the car during the actual heist, but he was nevertheless part of the overall effort. Another situation where I think “common purpose/joint enterprise” applies is one person hiring a second person to murder a third person.