There may well be incidents of ageism at BN. I myself never saw this. I worked at several different stores in my career, and while corporate is guilty of many stupid things, as well as being mendacious, money-grubbing, and callous (layoff nearly two thousand experienced, dedicated booksellers and then advertise, during the last holiday season, "Let our experienced booksellers find the right gift!"), nobody, at least to me, ever sh--canned a bookseller because of age.
When I came up and learned managing people, it was in a different trade and in a different time. The older guys who taught me made it clear that, as a manager, you would take a bullet for your employees, period. You might not like a guy, or even think of him as a good employee, but if he was on your team, and he was behind the eight ball, you stuck up for him, because that was the way things were done. I was particularly lucky in this regard at BN for many years, working with and for people who had the same philosophy.
This might not have been the way things were done in other stores or other districts; I knew of store managers (and worked under a couple) who were really revolting human beings and really bad managers, so I'm sure that bad things happened. In this particular case of ageism, however, I certainly never witnessed it.