I really dislike dogma, except when I am being dogmatic about aging
. I very much doubt that a panel of smokers with great palates could tell the difference between a tin never opened and tin opened and closed. Pease and others said that aged tobacco has volatile essences that support/contain flavor, and thus if you open a container of aged tobacco ,you should smoke it quickly lest they dissipate
But so much of pipe lore is entirely subjective, and quantifying these claims impossible. In any case the final status of this container's properties is a very different matter than SG or GH's bulk tobacco in makeshift packaging sitting on some tobacconist's shelves for months. In the latter case, by whatever means, the tobacco does suffer. It can be brought back, but perhaps having lost 20%? of its goodness.