If you don't want to read my rambling...just read the conclusion!Who knows what actually went down and how. However, keep in mind that EPMB (Mark Burnette) is telling a story and there is a reason he didn't show us why Joey decided to give away the truck. Until we know the real reason there is no way I can judge whether it was a good strategy or not. Who knows?
If you remember Jesse gave up first and then Joey stopped at the finish line. I think Jesse and Joey threw it on purpose to hold it over Manfredo's head to get the matches they wanted. IMHO! This could work to get them to the next round if they get the matches they want and if neither of them want Manfredo (we saw Jesse back down) then manipulate him so that if he (Manfredo) wins a challenge he picks someone else other than them.
I think Jesse is the person that is manipulating this game to his advantage. EPMB never revels the strategic moves until he has to...it is the same way with Survivor. The story has to be compelling with twists and the only way to achieve this is by keeping some of the manipulating from us. The saying we have over on the spoiling board for this is "an alliance shown doesn't succeed".
Conclusion: I think Jesse and Joey are trying to manipulate Manfredo in getting the matches they want and they are using the truck to get the leverage. Mark Burnette never shows the manipulating until he has to!