Because Brad’s his manager now, so it is his role to tell him:
1- how important Twitter is and that he should definitely do it himself and explain to him how to,
2- if he REALLY doesn’t want to do it, it’s Brad’s role to find someone qualified for the job and make sure to keep his account alive with interesting content and most of all, make sure the fans don’t know it’s not David handling it.
3- if David REALLY insists that Brad does it himself, it’s his job to ACTUALLY TWEET STUFF!
Brad is bad at his job and it really affects David’s job so yes, I’m blaming Brad. Always.