Cop, glad you got to play the demo. In that demo, I can see a co-op somewhat. A lot more crazy hectic scene than any in Swat4, but I think you can still get a co-op game in the demo.
I would have played it this way (lets say its a team of 5 ppl):
2 - stay back and zoom and snipe people off the roof
3 - leading like forwards in soccer. 1 cover the center, the two other covers right and left.