The bolded is incorrect. It is a crime, but the FBI is using the argument that in general not every crime committed is prosecuted, and under similar circumstances other people haven't been prosecuted for this.
You seem to be ignoring Comey's important point: "To be clear, this is not to suggest that in similar circumstances, a person who engaged in this activity would face no consequences”
The consequences he is referring to are things like getting fired, having your career ruined, etc, etc.... at best a person who did what Hillary did would keep their job only if all access to sensitive data is stripped from them. Promoting someone who did this is insane, and I think people who want to promote her are committing a worse crime against this country than the one she committed.