Lyman,
The rule David is referring to says the SCPF is "recommended" to prevent the course from turning up short on re-measurement. So what Blane says basically reflects what the rule says (although like you I would have said "unlikely to" rather than "not possible to").
I don't know that we should read more into the SCPF than is really there. Just a mechanism to avoid verification failures. If the USATF/IAAF record rule was that the course couldn't be more than 0.1% short, I doubt we'd be using an SCPF.