I doubt IBM lays off its older workers solely to appeal to Millenials. It's more likely that older workers are laid off because they are more expensive due to higher higher pay, have more paid time off, use more healthcare and are more politically calibrated to their organizations than younger workers.
It's more likely that older workers are laid off because..
This is just a list of rationalizations that you would prefer to believe. That doesn't make them true. If those reasons were actually correct then IBM wouldn't need to fire people. They could solve all of them in other, less (potentially) very expensive ways.