pigx5,
Thanks for taking the time to post back. AMEX can see the difference between ITIN #'s and SSN's. Each SSN is assigned in a way that they can get information from it (where it was applied for/assigned, etc).
I have heard that some banks have issued credit cards to ITIN's but AMEX is typically much more stringent in giving out their cards. For example, my wife wasn't from the USA but for tax purposes I had to get an ITIN for her to do my taxes.
With the ITIN she couldn't get an AMEX card but shortly after she got a SSN and she bought a car and I added her as an authorized user on some of my cards, AMEX gave her a Platinum Card.