When they made the "generation" change in 1995, where they appeared to try to quietly drop it, that was when they had the opportunity to let it fade away. Once they revived it with the 'overlapping generations' explanation, they effectively doubled down. Now they are committed to it, like it or not. If they try to reverse it now, it would be a glaring admission that they were stumbling about in the dark the whole time.
It's possible that they felt they needed to address it somehow, and adding fifty or so years to the explanation lets it fade away without them having to ever talk about it again. But that just kicks the can down the road. They won't be able to handwave it in 2076, assuming they're still relevant at that time (or that they haven't shut down by then).