Although, the repository seems a bit... Weird. The README ends with:
> This is not an officially supported Google product. It's released by Google only because the (original) author happens to work there.
Why would Google release it if it's not their product/project? Why is it under github.com/google? Do Google own projects that people happen to work on in the free time just because you otherwise work at Google? Something smells fishy here, but wouldn't be the first time Google does fishy stuff.
* Have a "fairly flexible arrangement" to work on side projects when they want & potentially using Google hardware on work time but in exchange Google holds the copyright & it has to be published under the Google repo with the quoted disclaimer.
* Deal with a bunch more paperwork on per-project basis.
If people don't have a particularly strong attachment to their side-projects the first option is the "low hassle" option for flexibility to do side projects at work.
I would agree it is unfortunate developers don't push back harder against such a wanton "IP" grab by their employer--but hey, I guess that's what we get without collective representation or respecting our own value as developers.