If a hacker can get inside the computer of NASA some years back, any determined hacker is certainly not going to let Aadhaar-linking impede their abuse of social media, for the simple reason that the offending account would in any case be a false one.
So how would a hacker open a new account (assuming linking is already in effect) is the real question. Simple, like the fake account would have an email ID that anyone with internet access can create, they would also use a random Aadhar from a database created by them!! Shocking revelation? I think not, with data leakage being a major cyber-forensic concern!!