Why do you believe that churn is a good thing, especially for a thin wrapper around Linux namespaces? There should not be much this is actually doing, so lots of commits would be worrying.

Last commit 19 days ago. Code commits merged into master seem to be around every 3 months for the last couple years.

That seems healthy to me.

As for documentation, it seems to have monthly or bimonthly updates.

The question in your issue is that their is a lack of activity... Came about three weeks after a commit, and two weeks before another.

The issue just seems to be that rkt prefers their mailing list to GitHub issues, though they do pay attention to both. And I don't see a problem with that.