Thank you for pointing this out. I've added metadata for the trail in changeset #169083272. I've added the name of the trail, difficulty ratings, marked the trail as unsanctioned, and added a description.

The trail looks to be within Whistler's Controlled Recreation Area and therefore may have a legal access restriction. I am not up to date on the legal restrictions of the CRA and therefore did not add a legal access restriction.

https://www.openstreetmap.org/changeset/169083272