I think Garrow is getting into sensationalism here, to be kind.
Should Garrow care to name his source, he won't seem such a scaremongering freak.
Military members swear to support and defend the Constitution, not support and defend the President.
Furthermore, after the Civil War, Posse Comitatus Act gets quite detailed about domestic use of the military.
The debt and deficit are far greater concerns.
Not that we shouldn't keep an eye on #OccupyResoluteDesk, mind you.