Age would matter for a startup beyond just skills. Older hackers might not be able to "keep up" and "fit in" with many startups. Culture fit is really important, but being old doesn't automatically mean no fit.

One interesting thing about a hacker being 50 is that they potentially have an empty nest (no kids), much like their 20s. In some cases they might be able to work "startup hours".

i think if you're a 50+ year old tenured professor, your skills are probably not in line with what a start-up needs; you've spent 25+ years of your life optimizing for doing academic research and teaching, not sweating out the details of making product X work seamlessly on platform Y with quirk Z.

some 50+ year old tenured professors co-found companies and serve in advisory roles, but i highly doubt that they're staying up late setting watchpoints in gdb and punching their monitors.