Also it is the collectables section after all, regardless of what is being sold or raffled, and an NFT is a collectable item.
Personally, I would think if you were selling tickets for Bitcoin, then you could probably put it in that section without much of a problem. Due to it being a raffle for free entries, and then the actual thing being raffled being more related to altcoins than Bitcoin, it probably does fit in the Altcoin section better.
Many things in the collectibles section aren't strictly related to Bitcoin, but are using Bitcoin as a method of payment, and therefore are on topic in that section. Its a bit like the services section in that regard where services could be related to theoretically anything, but must be accepting Bitcoin as a payment method to be on topic.