The Rosie and Moore incidents were symptons of their demise, not causes. As noted earlier, they had many questionable business practices and decisions, perhaps reflecting on how they wish things to be rather how things really are. If it works, it's visionary; if not, it's stupid. K-Mart was stupid.
I suspect it has less to do with their stance on RKBA specifically, and more to do with the fact that they don't provide the services and products that the American people are looking for in general.