If you are going to use public commit profiles as part of your screening process and hiring decisions, I would encourage you to ask candidates what aspects of their public activity are relevant. For example, ask for a few specific highlights and why the candidate thinks those are interesting.

Hobby projects and open source contributions are evidence of patterns of collaboration and commits, but may not be indicative of one's typical (or best) work. There are also many reasons why a great software engineer may not have a public activity profile.

The majority of my public commits are scratching itches on open source projects, and are very opportunistic depending on other life and work commitments at the time. Code may not always be pristine, but I can probably rationalise why I took a certain approach (following existing code style, hacking for my own use, actually aiming for quality and performance, ...).

As a hiring manager, I'm also OK if candidates want to do something with their personal time that doesn't involve committing to public repos :).