Jeez, an entire two page thread for this paranoia?
Let's see, you said he was polite and professional, right? What's your beef with that? Give him some credit, what with having to deal with a-holes, thugs, potential cop killers, and city council people.
He had probable cause to stop you whether you and the others want to believe that or not.
As for your SSN, there are eight of us in this area with the same name, unfortunately, so I'd gladly provide my SSN to a professional police officer who wants to ensure I'm not that one of eight who has a felony warrant outstanding for aggravated robbery.
If he remotely suspected that one of eight was me, how would you EXPECT him to react?
And c'mon, cut the [censored]. ID theft is a cop out (pun intended) for not wanting to cooperate. You have a substantially greater chance of having your ID stolen via online B.S., a credit card transaction hijacked by a skimmer at a gas station or ATM, or via your monthly "charge my credit card each month for this recurring bill," than you would a cop selling or using your SSN.
If that was his intent, he could have easily obtained your "vaunted" SSN later by running your name, date of birth, and driver's license number through one of several databases.
So, why did he need it at the moment he stopped you when you appeared to be heisting batteries? It resolved any potential question of your identity.
Case closed. Move on to more important things in life.