I'm surprised to see, exploiting Airdrop this way. Imagine paying $5 to be your referral; its like hitting two birds with one stone, making two profits at the same time, There are other platforms I've known that do this; they do their research and post it on their platform in exchange for signing up to their referral link.

So if ever you push with your project, are you going to disable the referral link because people paid you to find good projects, If you are going to include the referral link, it can be considered abuse, they paid you, and you made profit from your effort.