Sidenote: if you're interested in doing the same just go to http://www.getgrandpasfbifile.com/
Also, I wouldn't be surprised if the email server suddenly lost a bunch of emails the day before the FOIA request went through.
"It does not require a majority to prevail, but rather an irate, tireless minority keen to set brush fires in people's minds." -- Samuel Adams, Founding Father
I'm one of those folks that when I see a redacted email like that with most of the identity cookie in it I wonder if one could track down the original. I mean mail.fourtentech.com actually has a web server sitting on it and all.
Anyway, it could be a viralish stunt, but sadly its pretty credible that the TSA might say this.
[1] http://tsaoutofourpants.files.wordpress.com/2012/03/caution_...
I do not however see an email that looks like anything from Sari Koshetz with or without redaction.
EDIT: I agree with the user "martey" below, though, that this wouldn't necessarily be evidence of anything. It's way too easy to fake this kind of thing. The FOIA request for the email is the way to go. It'll probably find itself conveniently deleted or something, though.
Or an infinite number of other things. Don't get bogged down in what the alternative scenario is. What is important is that if something is true, we should be able to find corroborating evidence to support it. If we can't, then we have reason to doubt the initial claim - and we can do so without arguing for a particular alternate scenario.