They aren't stainless screws they look like they may be hardened tho. They do seem to punch into a poorly threaded box ear easier than the stock screw with no thread damage and the head fits the phillips bit a whole lot better that the "whatever you have" head design.
I can see why he likes them
Stainless screws are actually pretty soft. I do use stainless screws on outside boxes at my house but I am the one who will have to get then out in a year or two.
The only problem I see with using drywall screws in plastic boxes is you have no fall back position when they strip.
When I saw the first one, I assumed he stripped out a 6-32 but they all seemed to be drywall screws. I guess he figured they were just faster or maybe he didn't like the originals with his power driver too. Drywall screws are "free" when the rockers leave. They are pretty much everywhere.
