For a hobby, sure. Its fun and novel while a few documents sitting on S3 is boring. But from a practical and environmental standpoint, it's purely worse. The OP link is currently dead while I've never seen github pages down after years of using it.
From a practical standpoint Open-Source software is often also a hard sell, if you ignore the value of the gained freedom. This linked project isn't much different from someone running Gentoo with Libreboot and a custom kernel. Is it necessary or practical? Maybe not. Environmentally friendly to recompile everything? Nope. But that person probably learned a lot in the process and had some fun with it.
> I've never seen github pages down after years of using it.
Sure, though with those services the actual uptime doesn't exceed the user account's lifetime.
As hobbies go, I think it's practical. There are applications where handling things in the cloud just isn't an option. Many of them are also cases where you don't have reliable power.