What's the difference if it's Airdrop? You get their tokens for free and just wait and see, maybe you can sell them.
This is really fake! Any airdrop that is asking for private keys is scam. Why you give your private keys? Its just like giving your keys of your house to the straner. Beware of this. Better download a chrome extension like the "EtherAdressLookUp" so that if you visit suspicious site, it will alert. Most of airdrops are shady, posted by a newbie with no any info about them. Some are just collecting twitter followers, emails and nothing else.