Tomato tomahto. Whether its called airdrop of frozen drop doesn't really matter here. What matters is that they sent tokens to those that never asked for them, never applied, never registered. But luckily, their little scheme is not working as good as they thought it will.
I am one of their receiver I never asked it or registered for any airdrop just surprised that I have this but this is free money, if the way to claim will be easy and I can do it within my means why not claim it, but they must prove that they are profitable or those who received airdrops are not going to lose anything.
You are right, in order to get credibility for their exchange they did an Airdrop and this will not help them to get a reputation because most of the people will sell their coin in the exchange if they don't keep any restriction to the people who have airdropped. Most of the people will not show interest in buying their tokens.