Typo here, I think.
I agree that this underplays the risk. It’s worth noting that there are (at least) two kinds of risk: security and stability. The stability risk of testing can be quite high. Users who need their systems to be stable (e.g., can’t afford down time or lost work between backups) should not be doing any testing on those systems.
I’m also fine either way. Might get more uptake by publishing a Qubes news post and usual syndication via social media venues, or might not if all would-be participants already see it here and on qubes-testers. If you want to do it, let me know. (We could probably just use an amended version of this post with you as the author.)