Probably a sub-issue more than a side issue. Its one of Paul's positions (among several) that is often cited by those who dismiss him as a "kook". The derision directed as calls for a return to a gold standard, even among conservatives, is an indication of how far America in 2007 is from a government operating under the Constitution. A gold-backed currency was, at one time, accepted as the only Constitutionally legitimate form of money. Calls for a fiat currency would have been dismissed as "bizarre" and "kooky" just as calls for a gold-backed currency are now. The same holds true for many of Paul's positions (eliminating the IRS, returning to a non-interventionist foreign policy, doing away with the federal entitlement system, etc.).
This is RP's problem...and the problem of any candidate who is faithful to the Constitution. I think that's the point Derbyshire is making