Hey, nice idea!
If i understood it correctly, then zombie can push you back.
Now imagine the situation, when you are behind a wall/small house/on a house/behind a car... (list can be continued!) and some1 pushes you back through the object.
So your system is not bugles, what means u have made a new way to abuse a bug.

If i didn't understand your idea or something then please take my apology!
And this post wasn't made to criticize you or your system/server/idea( i actually liked your idea

). I just posted it in case you didn't know about it.
Kind Regards,
Luxeon
You don't have this problem with SetPlayerVelocity, if this was 0.2x we would of had to make this with SetPlayerPos and then yes you would be able to go through objects. If you watch the first part of the video he was pushing me in to a wall of the building I did not go through the building I only was falling against it.
THIS IS WHY I LOVE SetPlayerVelocity

It actually has collision detection.
Thanks Kye and the Dev's!
[Edit] Wait after reading you post again I think I miss understood, if a player is say on a roof (victim) the zombie yes can stand on the ground to push the victim off of the roof ( I intended for this ). As long as the zombie is within range and exactly facing the victim he will push him. Now the behind the building is well possible to do although very difficult because you can't see the victim in order to face him exactly to trigger the attack.