Or maybe it’s that mystery person that was following Rick and the others around; perhaps this is a test of some kind.
Additionally, maybe this walker is the product of Michonne or another good guy, meant to throw the Saviors off.
Keep the conjecture going in the comments, guys!
Comic fans know that there is a point when Negan and his crew do utilize walkers for weaponry goals in their war against Rick’s group, but it’s done in a much different manner on the page.