Doc stands his ground, not quite sure why he should be anticipating a fight but feeling like not doing so would be a big mistake.

Finally when Negan backs off Doc is able to breathe a small, relieved sigh, adjusting his hat and reaching inside to pull out bundles of clothes.

"Back in the cupboard. We only need what seems useful." Either he's exhausted and still hung over or Negan just drains the life out of him.