Well we know there is at least one survivor.
Perhaps not on the side you hoped.
He seems to have pets, or perhaps followers.
If he is the only one of his kind then survivors in other areas might destroy him.
Think we can get one of his rodents to rat him out?
We can always leave the destroyed zombies as food for the rats.
Providing they like it they might lead us to others.
How far can we go?
Would you leave a zombie to rot?
Or would you burn it?
Could you follow the rats as they sniffed out more food?
Which is better follow rats or find them yourself?