There isn't much of a disagreement. You say, " Whether he leaves feedback for the seller shouldn't influence whether he receives feedback as a buyer."

In my post just above some, I said "As a seller I DON'T only wait for positive feedback from the buyer before I leave positive feedback for the buyer. I do this:
¶ if the buyer leaves positive feedback, I automatically right-away leave positive feedback for the buyer.
¶ also, if several weeks go by and I have not heard from the buyer (good: no problem), then I leave positive feedback for the buyer. "

I leave positive feedback for the buyer if several weeks go buy and I have not heard from the buyer (that is, no complaints, even no feedback from the buyer to me).

Robert