Yeah that seemed like a weird restriction - "Silver rails only".
Maybe they're worried the bars will damage the black finish or may not grip the black as securely.
I just got a set for my SE last week and scored with 25% off (though I had to pay shipping).
Just purchased an SE last night in Pure Gray and the seller hooked me up with the rails and bike rack attachment. They needed to order it because they didn’t have the parts in stock, I can’t wait to put them on!