In any case, none of this conversation is at the level of a dissertation, neither enough time or space.
The start was a seven-word comment with a tone I read that was entirely dismissive of even the concept that IBM could be practicing ageism.
It cannot be dismissed so easily (and I have family working there trying to evade exactly those ageist axes to get to retirement with full benefits).
The point of the smoke/fire is that a single good counter-example of disparate results likely not implying discrimination does not disprove all examples. The fact remains, such statistics remain a good starting point.
You have many words, but beyond the first general wave of the hands that statistics do not imply discrimination and one non-correlating example, I've missed where you provided any info or evidence to show IBM is not practicing ageism, in particular to effectively cut pensions.
Since IBM are clearly managing the workforce for profit, the multiplier of cutting older people is far larger; you save not only a few years of higher salaries, but also up to decades of zeroed or reduced pensions. Pretty strong financial incentive.
Between the two of us, I am looking at a well-researched and widely understood example of why a disparate outcome doesn't actually imply what we would intuitively think, while you are talking about metaphors of smoke and "taking closer looks" as if those justify angrily jumping to conclusions.
If you have some sort of correlation coefficient to justify jumping to conclusions even mildly, I'd appreciate that contribution. But "something isn't equal" isn't even necessarily reason to look into something further, let alone a reason to presume the cause. Nothing is ever equal. Equality is a fictional concept, and doing deep dives into every example of it would exhaust our collective resources.