"So to solve the common problem of the guy who stands in front of the doorway, blocking his entire team, we don’t have collision between players at all. So everyone can walk through everyone. However, to ensure players can’t take advantage of this (by having a small body-type player “hide” inside a big body type) players will get gently “pushed” away from each other if they stop moving."
This implies that there is no collision within a team (like in TF2), it does not state whether or not you can impede an enemy by standing in his way.
If you can just walk through someone, what would be the purpose of a trying to block the enemy. They could just walk through you, backstab you, and be on their way.
Also, a light can hide behind a heavy. On a charge for cover, a light could use the heavy as a meat shield to get there unharmed (provided the heavy player is willing to cooperate).
*PS I didn't know you were with the Resistance... welcome aboard http://i298.photobucket.com/albums/mm252/mysteryom100/untitled-1.png