If you cancel the AI targeting of player entity then you get the same sort of effect where they go crazy and randomly smash the world up.I see your point. I feel the problem isn't the zombies digging, but rather the logic they used the past. They dug everywhere, willy-nilly, causing the swiss-cheese effect on the landscape. If TFP can fix this, then I see them as a viable threat...
-A
I did think think about this when i was trying to get zombies target certain block types.
I tried to add the tag "door" to see if the follow ai task 1 but that didnt seem to work.
But if they could use the tag system and when you placed a playerblock on a terrian block and it basicly modified 2-3 terrian blocks vertically that they where glued to with a targeting tag then this might work.
The fact that the tag is already a property means maybe no extra overhead on the block properties.