Or perhaps just stop the idea of airdropping all in all? The thing is, a lot of people are joining airdrops for the money and not really adding some substance to the community. Kind of like robbers in broad daylight. I understand that this is a strategy to get some more people on board the project, but it risks the investment of those who actually paid to get in on the coin. It's not being selfish to restrict airdrops, but it's a smart move to lessen coin dumping all in all.
Actually, airdrops is not always about new projects. There are projects that have already had working platforms but they didn't launch their tokens from the very beginning, and they do it now and reward early or active users. There has been a case with a paraswap recently, also there is an anticipation of Metamask's token so if the project is already famous and just want to reward its users, I think that people will not sell off it as they will believe in prospects of the project.