Nope, it definitely disables MDS in my truck. I've tested this extensively; cruising down a rural road at 50 mph, no wind, no towing, no weight in truck, just me. MDS kicks in of course. Flip TH, instantly MDS goes off. Flip it off, MDS comes back on. Like clockwork, 10 times in a row.
If you want me to provide a video, I'd be happy to try and create one. Otherwise, I'd be interested if you could do the same test, perhaps we're not all running the same software and it works differently.
But I suspect you didn't have MDS come on while towing 6500 pounds. Most trucks turn off MDS with 0 load attached on a straight road with just a bit of head wind hitting them. 6500 pounds is a very heavy load, my truck runs in 6th gear towing 5000 pounds, there is absolutely no way MDS is getting activated, in any gear, at any speed, while towing that kind of load. It just can't run on 4 cylinders while doing that.