Personally if I am on the server, if the map gets swapped to Sorrento I warn players that if they close the back door on team-mates and it results in a team death I will slay them. However if the door closes and no deaths that's fine because you can just go around the side of the house and jump over.

As for Shroom, if you shoot the zombies in the cage is doesn't actually achieve anything as the zombies get 10,000 - 50,000 HP and it actively regenerates however you're not helping your team which could really if you think about it be classed as sabotage.