Centurion is the formal name of the American Express product often called the black card.
Until 2017 the USA version of International Airline Program was primarily a "companion" ticket benefit, which did not offer much to solo flyers.
In which country is his card issued?
I did not apply for the Platinum until I found that the companion ticket program was changed to IAP. The companion program was pretty much useless even when you are travelling with someone as you need to buy a full price biz class ticket in order to use it. (Which is always >2x a discounted biz ticket)