In the Army, the signature on a letterhead document would be "Commanding" not "Commander." True for the Air Force?
Compare the alleged Memo/Order with one of Kerry's orders from his own website, which is typical of the format I saw in the Army, adjusting for service differences. Note the different typeface and format. http://www.johnkerry.com/pdf/jkmilservice/Bupers_Orders_To_Gridley.pdf
Actually, "Commander" is the correct Air Force signature block designation.
The Air Force had a little twist where they would allow someone to sign as "Acting Commander" if the commander was off station, but they eliminated that allowance in the late 70s. Someone holding appropriate delegated authorIty might sign something "FOR THE COMMANDER" (all caps) too. Only someone on G-series orders was allowed to sign as commander.