You don't have to repel the cargo raider, you can also kill him ... which is much easier if you ask me. Make sure you first target and take out the RzR/F's before heading toward the PES. They pose the greatest threat in this mission, but shouldn't give you a hard time.
Keep in mind that there is an error in the mission if you are playing version 1.0. The game states that a mission objective is complete, when you only inspected 97% of the cargo.