I do have the gift certificate the OP showed. I took my TAs word for it that it would not apply, because she checked with Oceania and that's what she was told.
It does seem as if this type of "gift certificate" is designed to get people to book early and it did motivate me to do so when I would have waited a bit. But my guess is that it is basically worthless unless Oceania has NO offers of any sort available at the time, which never seems to happen. It would likely not be available to anyone at Bronze level or above, since that qualifies as a perk.
I will send it in to Oceania and let you all know what happens.
Mary