May I suggest banning airdrops entirely? The first airdrop was fine because it took people by surprise so there was no chance of certain negative behavior being “incentivized”.
However, every airdrop that occurs after that initial airdrop is going to lead to negative incentives. This will happen regardless of whether someone states their true motives or keep them concealed. Far better for us to give up the idea of airdrops, period. If you don’t want people to contribute because they want airdrops, then get rid of the airdrops.