Lol, you've never opened a gmail account using fake data and sent from there? Yahoo? Hotmail?
The FBI will help your sys admin investigate a bomb threat, obviously. Reporting a security hole will unlikely draw their interest. Yes, just using a fake gmail account is tracable without more protections (like correctly accessing Tor). Again, I doubt the FBI is going to investigate.
But hey, I'm all for paranoia and extra caution.
Plus, rtfa you linked. It says clearly in the first few paragraphs that Tor did NOT fail this guy, but that he's an idiot in how he accessed it.
Lastly, as mentioned, send an anonymous letter. It's not hard, kids!
If what you're reporting is significant enough to threaten the livelihood or reputation of people important enough, they can and will find a way to trace you via your fingerprints/IPs … or do you think Google won't simply roll over on you when they get a subpoena/warrant?
The issue of anonymous disclosure is a real issue if you don't
Why do you think Wikileaks was such a big/new deal?
[1] http://www.forbes.com/sites/runasandvik/2013/12/18/harvard-s...