Well, on other exchanges do not give anything for registration. Let's say this is not an incentive to register, but rather as a nice bonus. You can buy some tokens of young and promising projects for the money and who knows what amount will be in a year!
Why not hold regular airdrops coins that come to the listing on the stock exchange on the site of the administration of the exchange? Many exchanges do this and this is popular among users.
You are a stupid man. airdrop, works only to collect a lot of fake accounts, but it can not collect a users community.