I ran into this today when I was testing nooblife in anticipation of the world reset.
When you agro an ant and then go to a place it cant reach (i.e. inside a cabin or onto the water.) and then put ure combat to not wanting conflict (make the two swords icon into a branch and sword) you can attack the ant all you like and it wont try to fight back.
Edit: okay I just tried this:
I agro'd all ants around a mound and did the non agro glitch described above. when I now raid the nest the ants are all apathetic about my ruining their nest.