Finally I could see some of their team members include their CEO in their official twitter account. But I do not understand why the airdrop information is just released in reddit? Not everyone has a reddit account.
If you don't have reddit account then you can't participate in that airdrop, because they only ask you to join the official reddit account in order to get 4 AST-NET tokens.
Yes, it is an exclusive reddit airdrop program. Just register on reddit (its free!) and you are ready to pick up your free 4 AST-NET tokens from the airdrop.