I have NEVER heard of such a thing. We had VIPs visiting us all the time aboard ship/while overseas. I can't imagine being told to disarm. If the Commander In Chump thinks our troops are that unstable/is in fear of them - he should bring them the **** home.
Nobody was asked to disarm when I met General Jumper and Donald Rumsfeld when they came at Kiruk in 2005. Granted I was Air Force and didn't have weapon but none of the Army on base had to disarm. The thought of it seems tarded to me.
That said, from what I understand this order came down from Major General Gurganus. If you have any proof that this order came from SECDEF of the CinC I'd like to see it.