So, let's see if I got this.
As long as someone is at a higher elevation on the trail, "above", till right before collision, it's the higher skier's responsibility?
In other words, if we took the same Grey and Red guys but separated them by say 40 yards. Grey starts first, he goes downhill on the right side. Here comes Red on the left, skis same way, basically straight down sliding tails left and right. Grey now begins to cut across the 40 yard trail, Red is still uphill, Grey comes all the way across and by the time he gets there T-Bones Red from the side. Just before impact, Red was higher up the trail.
So, it's Red's responsibility that Grey T-Boned him?
By Jove! I think you've got it!
So glad. Can we stop now?
Gray starts first. He's ahead. It's Red's fault.
...because Red's responsible for seeing the guy ahead and avoiding him,
even when Gray does something really stupid or totally unexpected.
Note that under Colorado law this is also perfectly clear. The uphill skier has the primary responsibility to avoid a collision under Colorado law.
So, even if Grey was skiing perpendicular to the fall line and truly T-boned Red, it would still primarily be Red's fault under Colorado law. Under the skier code's "ahead" they would both be at fault in that case, since each skier would be equally "ahead" of the other if they are coming at a 90 degree angle to each other.
So under both the skier code and under Colorado law, Red is ALWAYS at fault, even if he is truly T-boned by Grey. It's just a question of how much fault should also be applied to Grey.