So skimming the title it quickly I read it as "Open source projects should run on office hours" since my mind filled that in, kinda implied that someone in another part of the world should adjust their life hours to contribute to OSS.
(Yes after reading the article i realized that it was wrong but this is about the title)
> you know, the kind of hours that people typically work in an office.
It's exactly the same thing. There is no difference. This guy "works" in a home office on his project and he does so by talking with contributors (his customers essentially) instead of just sending a message on a mailing list or by posting on an issue tracker.
Where do you see the difference between this and a lawyer being open from 9-5 for customers? They are still his office hours and "office hours" primarily matter to outsiders who have to schedule an appointment.
For example, I work on a project that heavily depends on "library foo". The guy who wrote "library foo" (who is an employee of my company) holds "office hours" for one hour every Monday, where he commits to being in a Zoom call that other employees can join to discuss questions about "library foo". That does not mean he only works for one hour a week.
To a student with no professional experience, "office hours" are posted times when a professor is available to further mentor and guide a student. "office hours" are designated times outside of the scheduled class times and professors are generally required to provide them so others can benefit.
To a professional and others with white-collar jobs, "office hours" are hours are times when an employee must be seen by a manager to be considered working. Times outside of the scheduled work times are called "outside of office hours" and employees are generally expected to provides them so others can benefit.
Still, I am deeply opposed to formulating in ways that suggests any form of obligation/entitlement/expectation.
Though I expect that in many cases it would be a good and useful idea!