Seems simple enough.
So, applying the above and using the pictures from the other thread....
Please note the open sections of the run/area in question.
Or Tballs graphic...
Remember, both sides agree that the skier traveled 120 linear feet, and far, far less vertical, before descending downhill.
... Or the fact that pre-incident, Prima Cornice was listed as a singular run/area, and was listed as open this particular day. So what part is open? If any uphill travel on the A-Basin traverse (.0000001%) means I am entering closed terrain, I'd better bust out my micrometer- there are quite a few dips. What about that one guy who sticks a ski a little higher into the high-side fluff on the traverse? BOOK EM DANO
The slide in question happened a good distance below the ridgeline. Far enough below where it is certainly possible for a skier to have traversed from the open gate right to the same spot with no uphill travel.
So.. No. I don't buy it. Instead, I look at...
1. Finding no evidence Vail referred to "upper" and "lower" Prima Cornice runs/areas pre incident, just gates. Trail map shows 1 run. Website listed the area as binary open/closed, and showed it open the day in question.
2. No evidence any person has ever been chastised, EVER, for entering the "closed" terrain by taking the goat path. I get what you are saying that unenforcement of a rule does not make the rule go away, but first you have to establish the claim that the run was closed, instead of an opening in a gate. It is not that "Vail has a duty of care to prevent people from circumventing its closures," it is that Vail has a duty to define what terrain is actually closed! I don't think their intent was to close that terrain, just limit access. After the incident, suddenly that changed.
3. I have seen plenty of situations where ski areas restrict access to open terrain by closing the most convenient gate- forcing skiers to spend more effort for access. Usually this is because of tough conditions or an abundance of low-skill skiers, and not wanting to convene a toboggan party. Just because gates are closed does not mean the terrain is closed- it might, but this is not a universal, and it does not appear (to me) to be the case here.
An additional real world example- Waterfall area at Wolf Creek. 100% lift served. There are plenty of cliffs up to 50 footers. To prevent unintended launches, patrol practice is to run a ropeline with an access gate just above the largest cliffs. The access gate is at Waterfall Gully. Access to Snake Rim and Big Drop, one of the largest cliff features, requires entering the Waterfall Gully gate and then sidestepping/hiking uphill from the access gate. From Waterfall Gate 5 on the other side, it is also an uphill hike once inside the access gate on Navajo Trail. By your argument that travelling uphill enters a closed section, Big Drop can never be open.
Alternatively, there will be times that the Waterfall Gully access gate is closed, but Gate 5 is open (usually Waterfall openings are binary- everything open or not, but I have seen this case on rare occasions- like when avalanche risk is very high on N facing slopes, and much lower on other aspects).
So Gate 5 is open. Gate 5 is in a low spot even though it is primary access for terrain on both sides- including terrain uphill on both sides. If gate 4 is closed, and Gate 5 is open, does that mean that travelling uphill to skiers right (towards gate 4) I am entering closed terrain? Even accessing terrain that is closer to gate 5? At what point do I enter closed terrain?
This isn't binary, and I think what this incident has shown is that in the age where skiing off-piste slopes as opposed to cleared runs is now the norm rather than the exception (and ropelines that used to run down the treelines on cleared runs are pretty much a thing of the past) what we have is a situation where what terrain is open and what terrain is closed is up in the air. It needs to be better defined (which we both agree on), and I think if we are giving Vail a pass on this (in my eyes) ridiculous argument that the terrain was truly closed, hitting them for improper signage of the closure would be appropriate.
If in the above example of Wolf Creek, if a hypothetical skier entered gate 5 and traversed towards gate 4, and was caught in an avalanche somewhere in there (with no signage/rope indicating where the closure was within the area that was accessed via an open gate), then I would see the ski area at fault too.
Avalanche mitigation is pretty damned worthless if closures are not effectively defined, and in many real world cases, what is open and what is closed is far too murky than what it should be (and changes the instant there is a problem, which is what I believe happened at Vail). If it takes a full containment rope to define it, so be it. I feel that is better than the situation today.