Well, this is at the crux of the question: Does a Diamond with a card have higher priority over a Diamond without a card, regardless of other variables? Using the newly-published ranking, one would think no if the Diamond bought Comfort+ or is a MM (since the card is 4th on the ranking algorithm), but as I have quoted above, the verbiage below the Priority ranking chart says that those with the magic card will have a higher ranking "within their Medallion group." Interpreted strictly, it means Diamonds (aka "Medallion group") with a card have higher priority than those without, because that part of the verbiage has no nuances to address higher cabin purchased or higher MM status.

Once again, I think it is just sloppy writing, but it is far from clear or definitive.