Remember how they smeared themselves in guts to blend into the walkers for a bit earlier? Walking around with two walkers chained and under your control would have the same effect I would say.
look at it this way. Hershel saw all of the walkers in the barn as people.. and shane told him it was nonsense.. to shane they were just walkers. when they saw sophia, they all understood hershel's point of view. the fact that EVERYONE put their guns down shows a huge hypocrisy on all their parts.. which just made it even…