Not trying to defend BRK, but wanted to point out something about Magnacut and other tool/stainless steels!
Some stainless/tool steels have different tempering cycles that can be used, which can effect the stain resistance of the steel. So heat treating can play a part in stainless steels staining. But Magnacut is not "stainless" in the traditional sense in terms of amount of Chromium in the steel percentage wise (D2 is just below "stainless" as well), but there is something to how the other alloys make Magnacut very stain resistant, 2nd to Vanax, even though by the % definition, it's not "stainless". Larrin talks about this in some of his articles about Magnacut and how some steels have 2 different tempering ranges that can be used. Most opt for the lower temperature cycles, which usually have better fine edge retention and toughness and stain resistance over the high temperatures, which are often used in industrial use so the steels don't overheat during use and de temper themselves.
I have also seen in my own shop with using the same belts/dunk bucket for carbon and stainless steels, sometimes stainless steels can appear to "rust" when I am at coarser grits due to the carbon steel particles still being on the blade and those rusting. I saw the pics online from BRK about the Magnacut staining, but they run it at 62 HRC and if they use the higher tempering protocols, the steel may be less stain resistant. If I scrubbed the blade well and cleaned it better, it stopped and stopped as I went up to high grits and the larger particles weren't getting stuck in the grit scratches.
I remember seeing some other brands, maybe Ambush and ATK, (removed the other company name since I can't find the info anymore).
They also did mid techs and produced production models for other makers at different points, too, as like a collaboration. They also helped a lot of smaller custom/semi custom makers learn how to make knives and helped them do batches and stuff, so a lot of custom makers got their start with BRK and went on their own from there.