I think maybe we're "talking past" each other, and I'm not doing all that I can to connect the dots. The details in that bit you posted from Western Wildlife Outreach matter and make a significant difference. Hunting between 1827 and 1859 - and 1859 to 1967 - are not remotely comparable to the hunting, or more accurately, the lack of hunting since 1967, or 1973 when the ESA went into effect. A key point here is that there is no record of grizzly bears being killed by hunting or any other factor since 1967. So everything that happened between 1827 and 1967 is notwithstanding when contrasted to the period since 1967.
So while the bears were relatively abundant historically, it simply cannot be said that hunting is a factor preventing an increase in the grizzly bear population during the recent 56 year period. Doing so is as misplaced and outlandish as blaming historical overfishing of Columbia River salmon in the late 19th and early 20th century for the low populations currently, when the most proximate cause of low populations is habitat destruction and degradation, especially in the form of dams.
This leads to the more likely reason grizzly bears have not increased significantly over the last half century - habitat. Just as deer, elk, and black bears don't spend all 12 months of the year in the alpine high country of the N. Cascades, grizzly bears probably didn't either, for generally the same reason: it's great summer habitat and really lousy winter habitat. If grizzly bears require a habitat mix of high and low elevation territory to do well, then I think we're getting closer to the limiting factor or factors. Low elevation habitat has been significantly modified by anthropomorphic processes, and grizzly bears attempting to occupy such habitat seasonally would inevitably encounter humans. From what I read, grizzly bears are less tolerant of human activity than their black bear cousins. Further, resources such as fish, are only 10 to 20% as abundant as they were historically in the anadromous fish zones. So a modified landscape with vastly more human activity and far less food resource, and someone expects the NCE to support up to 200 grizzly bears? It seems laughable to me. Given the factors in play, I don't see how a biologist or ecologist could conclude anything other than that the NCE is currently at its carrying capacity for grizzly bears.