The buyer shouldn't be making payment before sorting out the postage/pick up side of things. So in those cases, a seller wouldn't leave good feedback.
If the buyer paid and the seller had left feedback, then the buyer left negative feedback because "pick up only" was really "pick up only", then the seller can always comment on the negative feedback entry. Eg. "Buyer didn't pay attention to 'pick up only'." and the feedback mutual retraction could come into play when sorting out refunding the buyer.

