It's an old time trick that does a pretty good job of cleaning pumps and injectors as ATF is pretty high in detergent properties. It's not good to run it all the time as it will leave an ash deposit behind on the injector nozzles. I think on a new diesel with DPF and SCR it would be a really bad idea to run it at all for the same reason, ash.

On a non emissions engine I don't think 2 stroke oil will cause any harm as it's designed not to leave ash behind. With the exception of a 5.9 Cummins with a VP44 pump, I don't know if there is any benefit to it other than to feel better.

VP44 pumps are famous for "dead pedal" and I have seen first hand one cured after a quart of 2 cycle was added to a full tank of fuel. It took less than 3 miles and it's never done it since. It takes about a cupful every fill to maintain it unless it's bio diesel and then it doesn't need it.

Kevin