uh, you see this is what i hate about star wars. Because of this new thing about armor color having a significance, people are gonna get all worked up about why Boba, Jango, Jaster, Montross, Hokan and a bunch of other Mando wear the color armor they wear. The people who created/designed these characters just chose the armor color for no other reason than because that is what they wanted them to wear. But now with this new idea about color meaning, you gotta back-track and come up with half-baked explanations for why those characters had those colors.
It is just like the same crap that happened with the fighting styles of the Jedi/Sith. When KOTORII came along and introduced the different fighting forms, people went apeshit trying to figure out what forms Anakin, Yoda, Dooku, Kenobi, Maul and all the others used. The bottom line is that Lucas did give a damn about fighting forms, they didn't exist at the time. He just wanted the fights to look awesome (which they do) and hired a swordsman to teach the actors specific fighting routines that look cool, and thats it. There is nothing more too it. Same with colored beskar, its just cosmetic!