When he started on twitter he would post facts about GD songs and talk to fans/answer questions all the time. Then people kept being rude to him, and specifically were being shitty to him because he liked Lady Gaga and went to see her show (there's a video of him talking to a fan about this outside the AI musical) so he stopped interacting with fans on there and never really started again (and he confirmed that was the reason to another fan who met him).
Oh hey there's a thread for talking about Billie deleting (actually just suspending I believe) his Instagram now, so let's keep the discussion there: