This language now appears in the terms of all USA-issued American Express personal cards. I do not recall any report of the terms being enforced as written. Have you?
I have read reports of cardholders being asked during telephone discussions if specific transactions were Vanilla Reloads, but there were no consequences. This does not mean that the terms will never be enforced as written.
American Express practice frequently differs from policy, and usually in the customers' favor, but if practice is later brought into alignment with policy it usually happens abruptly, and customer service then has no flexibility to make exceptions.
During a FR, Amex specifically asked if I had bought VRs. It started with asking if I had made large ($500) purchases at CVS. I said "yes, I bought GCs". They responded by asking if I had bought VRs. I told them yes I had. They can most definitely see what we are buying (at least a FR rep can). They mentioned that they did not like this practice, but beyond that nothing came of it. And I then went on to pass my FR (even though my 2011 income was ~5k less than what I had reported on my Amex application in 2012). I have since not bought any VRs with that Amex card.