Everyone involved in this story was just plain incompetent. This story would make more sense if they were covering up for Tegan actually stringing fans along, because everyone is just so bad at trying to figure this mystery out.
The film doesn't figure out anything, and the story is sloppily edited. There's obviously more to these stories that were edited out to portray the band better. The managers who originally lost control of the online accounts and then decided to run the investigation themselves instead of hiring a professional are especially to blame. Tegan's weird manner while meeting her affected fans in the film was very off putting, with a hollow veneer of empathy used to gather more information out of them.
There's a whole industry behind cybersecurity today, just hire a professional researcher instead of playing amateur detective. I feel sorry to all the fans who were affected and will continue to be affected.