It's really more about how long it's been since you learned new stuff. Lots of programmers in their 40s learned most of their skills writing Windows apps and, at least the ones I know, are very resistant to change. If you just looked at older programmers who are open-minded and still learning then the numbers might be different.
Maybe it's that subset. Windows 3.0 was released in the middle of 1990 and it took a while for it to get red hot. Lots of programmers "in their 40s" should have "learned most of their skills" on earlier technology, e.g. UNIX and MS-DOS. Or mainframes.
I'm something of an extreme in that I was forced by finances to quit college after my freshman year and am about to turn 50, so it was a dozen years into my career before I started programming Windows (Charles Petzold C SDK level ... which I suspect is also not the sort of Windows programming you're talking about).
