I finally got a call back from the nice Lieutenant with the Capitol Police this afternoon. She apologized for the actions of the officer on duty and assured me that he would be spoken to about his dealings with the public.
I asked her specifically about the DL reader and in summary the reader is a convenience for the officer in generating the passes that attach to your garment. It is absolutely not mandatory that you have your ID scanned. Their procedure is to make sure that your picture ID, whatever that may be, matches your mug. If the officer at the desk tells you otherwise tell the officer to call their supervisor.
The Lt assured me that all on this detail would be given updated training to reflect this procedure. We report, you decide.
Thanks for the follow-up.