Purple is the typical color of climbing skins that are used on telemark skis, AT skis, and splitboards (see
www.splitboard.com) used to climb up mountains in the backcountry. "The Purple Pass" is a joking term used to refer to general backcountry use. If you wanna ski/ride it you gotta climb it first.
Later on a powder day at Rose when you're heading up Summit Six to hit the chopped-up snow, and you glance over at those bowls and chutes on the other side of the highway, you will see a few squiggled tracks on them. Chances are some of those tracks are mine.