They didn't say aging stops, but rather the death rates stop rising further after a time, which means that a 90 year old is as likely not to make it to 91 as a 99 year old would be not to make it to a 100.
But by then the rate of death per year is high enough that it doesn't matter much, and within a few such years such a person will be very likely dead due to the cumulative probability of death over several years.
They didn't say aging stops, but rather the death rates stop rising further after a time
They (Rose and his colleagues) do say that aging stops, and that is what they mean by it.
From the article: "The existence of an age at which human aging stops is no longer questionable, nor is its potential malleability." The point about that malleability is that if you can get aging to stop at an earlier age, this will substantially extend lifespan, and this may be a more productive research avenue than trying to make elderly bodies live longer.
http://www.bridgeplan.org/?page_id=42