Suppressing evidence sounds like something that would have happened considerably later, after they had reviewed Snowden's email records. Reviewing Snowden's email records seems like a reasonable means for the FBI to determine if they are dealing with a whistleblower or a saboteur. We are all convinced Snowden is a whistleblower, but the FBI isn't likely to believe that just because he says so.
Uh, it didn't exactly look like they were trying to figure out whether he was a whistleblower. It rather looked like they wanted to capture him and put him in solitary confinement, with little intention of going after those who apparently violated the law, to silence him, to stop him from embarrassing the United States government.
