Also, you do understand that people worked as software engineers even before Github became popular, or open sourcing to begin with, do you? So if someone is 60+ year old, chances are that most of his work has never been open sourced, and his work was targeting use cases, platforms, services which have no utility in this age any more.
Which have all nothing to do with how good a software engineer someone is.
And finally, do you have any proof that he never shipped any code into production?