This is not about the real project actually having a real airdrop or not; this is about the project making a name for itself and being popular enough that people know about them. Trending news about a project makes them a target for scammers, as newbies will be expecting the project to do some airdrop in celebration of their success or any milestone that they reach. So the SEI was worth the fake airdrop, as they have already built some sort of name in the crypto space.