Well, that's what they say but...
I use MM acrylic exclusively and you do have to thin them. Some of the colors are thicker than others but they all need to be thinned. You will run the risk of constantly clogging up the airbrush. I use 70% isopropyl alcohol as a thinner which works real well. MM does make an acryl thinnner but it is a little pricey. It's like 6-7 dollars for a 4oz. bottle. I mix with 40% alcohol to 60% paint.
Andy