I just had a manhunter pack of wargs show up.
I ordered all my colonists inside and forbid the doors with the intention of waiting them out.
They then broke down the door and started attacking my colonists. (everyone is ok now if you were wondering)
I dont know if the bug was that they killed the door or the text of the event needs to be updated as it now specifically says that they can't pass doors.
I suppose you could argue that by destroying the door and then passing through where it used to be they did not technically pass through the door, but that seams a little deceptive. :)
So, here's the thing: manhunter animals WILL attack and break down doors IF they detect a colonist entering that door. Otherwise, they will just wander around enraged until they get too sleepy or hungry and leave. So if you are able to hide everyone inside before any manhunter animals are close enough to detect them, it works as the event text says.
I believe this behavior was changed in some patch a while back to prevent cheesing manhunter packs by popping out from closed doors to take potshots.
But I think you are correct that the text of the event is misleading because it does not explain this.
It's been an A17 feature. They'll follow your colonists but if you have them repair your door they will leave you alone soon and forget it.
So basically to avoid this issue. Repair Door, use stronger doors, get inside faster to prevent manhunts from seeing colonist enter inside etc. Okay cool.