I dont know about Blue guns easily rusting, or the bluing wearing off. I have a S&W victory with 80% of the origonal bluing. MY service revolver was purchased in 1973. I wore it for 25 years in all kinds of weather, pulled from the holster thousands of times... and it's about 90% with some holster wear at the tip of the barrel, and the bluing is lightening on the back-strap.
Oxidation is the chemical reaction between the subject material and oxygen. Everything oxidizes. If not cared for stainless steel will rust. IMO Every firearm will rust to some degree, but is usually fine with a little TLC.