This game must act different for everyone. I just finished this mission, and let me tell you it was a trip. None of the AI players could see me...it was like I was invisible. At one point the same guy ran right over me 3 times, stepping on me everytime; except on the fourth go around I unloaded full auto on his butt right before he got to me :-) I ended up scoring 13,000 points with 29 kills and 1 vehicle (BMP) destroyed.
I hope when I go to retry this mission that the same thing happens again because I am really going to mess some stuff up.