I have to say, that message strikes me as a little strange. It's not saying you can't list a gift card, just says you can't list one in the gift card category unless approved and suggest you find a different category o_O - I wonder if that has anything to do with category-specific buyer protection limitations, since gift cards technically don't have PayPal protection? (eg as we know, some sellers will list protection-eligible goods in categories that don't have PayPal protection to try and compromise the buyer's eligibility, so perhaps it works both ways, and eBay are putting all non-approved seller's gift cards in categories that will mean protection is available by default).

As a side note, I searched the help pages for information about gift cards as suggested by eBay...check out eBay's 'suggestion' (the results when I clicked on full search were no better, none of them had anything to do with gift cards).