I have met him and he is generally a very decent guy, but like I said his perspective is informed by specific experiences.

That is probably true, but then you also have to look at the merit of those experiences. His fight has essentially been trying to make programming a "respected profession", where you contributions and time is respected. If that's the environment you're trying to create, then side projects are less important. Since your best work, excitement and learning is supposed to happen at work. Side projects might even undermine your efforts since programmers at worse workplaces compensate by having more exciting side projects. So I think the perspective is less that side projects are bad and more that work should be good enough that side projects (that leads to commercial products rather than hobbies) become unnecessary.