And it's not just about open source, it's about the author of this tool using trademarks and effectively impersonating Google.
Judging by the screenshot of the repo, I think most people who download this would think that it's official Google software.
That's because from what i gather so far it is a google repo with other tools using the same api they kept it in there since and even had it announced by the guy's manager at the time.
tbh i assumed that is an official product too
This is clearly something done in official capacity, during working hours, with the knowledge and support of his manager, who announced the CLI.
It says "This is not an officially supported Google product" because it's a DevRel sample/experiment, just like dozens of other Google repositories made by Google employees as part of their job.
Even some other tools in github.com/google have as much: https://github.com/google/python-fire / https://github.com/google/pytype/blob/main/docs/index.md / https://github.com/google/dopamine / https://github.com/google/go-tika