It's an excellent combination (the AA2000+Centurion Room), if you get the service comped like your client. Most people get a few comps per year from different banks, and it's not worth the use just for the escort through Immigrations.
I'm sorry to hear what happened to him during his trip to Egypt. IMO, Amex always gave the best service to me when traveling abroad and that's why I choose them (most of the times) over the others. About your client getting the Centurion Card, it's by invitation only and one must use a lot their amex cards for quite some time before getting one invitation. I'd suggest you tell your client to get a platinum card, and start spending a lot (specially in wine? :P).
The lounge is really nice and as he said, completely different to anything there is in EZE (and most airports in the world). It's worth a visit!