Because if you have 2 people trying to find and then spying on a couple of hundred, then it doesn't matter how good you are, you will probably die if you engage.
Unless you believe guys like John Rambo are real then it is better to call in a strike from the air or call in a greater number of your own to kill.
The whole point of these people is to sit and spy for weeks in a ditch watching who is there, what they are doing and why. If there is a pattern that finds Bin Laden is there every 10 days, then it is better to find that out than kill the rest in the first day.