I'll agree that the pressure drop will cool the air, and that was a good point that I hadn't fully considered. A little tact could have gone a long way though.
All I know is what works for me. There is flash rust, then there is flash rust. The degree of "flash" can vary. I aim to minimize the degree as much as possible without having to use additives. Time and temperature affect the degree of flash rust produced.
I prefer to tumble dry because I have found it MUCH easier to remove the media, especially from 1/2" necks. I don't tumble often enough to warrant building or purchasing a blow down system.
I found that I got much less flash rust by using cool rinse instead of hot. Moist heat is a recipe for immediate rust, while cool, fresh water takes some time to cause rust.
There are so many ways to skin this cat. When I fist started tumbling I found everyone had different ideas that they all swore were the "best" or "only" way .....dry vs. wet tumble.....cold vs. hot rinse.....pros and cons regarding additives...etc. So, what I recommended was just based on my experiences, and it works great for me.