Yes, flying suits and coverall are Protective Equipment.
The big difference, in this context, between aircrew in flying suits and groundcrew in coveralls is what is worn underneath. If the groundcrew want to walk around the station, all they have to do is take off the coverall, as most (and I appreciate this could be a bit of a generalisation) wear the dark blue shirt/ blue trousers underneath. For the aircrew to do the same, they would have to strip naked and then put on their blues, every time they leave the building. I often fly 3 times a day, and having to change clothes 5 or 6 times a day (in the fantastic changing facilities provided of course) just to go to SHQ or to the Mess for lunch would waste vast amounts of my already valuable time, as well as being a right royal pain in the arse.
Have to agree though about saluting the ensign as SDO, that should be done in blue.