I have not found this to be true. I once bought decaf by accident and had no idea why, over the course of the week, I was feeling more and more awful no matter how much coffee I drank. When I finally noticed that green label... man... I was on my way to the store immediately.
Regular roasted coffee, decaf or not, contains about five different acids. One of those acids is only processed by your stomach. Either type of coffee will greatly disagree with you if your stomach is compromised or removed due to illness due to that one acid.
Only air roasted coffee has a very low quantity of that acid. the Roasteriee in Kansas City and a few other places in the country sell air roasted coffee. Works for me as a cancer survivor but I still drink tea about two thirds of the time. I have become as much a tea aficionado as I was a coffee nut.