One time, I cleared the way for the FROG-7 before putting the mafia thugs in the transport truck. Then, when I returned to the mafia guys, they were unresponsive. I had to go back and deliver the FROG-7 myself
What I would assume is that the code for this is set up something like this: When (A, B, C) are dead, then the driver starts to drive to the destination. So, there is no 'AND the mafia are delivered to the truck' trigger-part.