Point taken. It is certainly true that this provision is distinct from the main goal of copyleft-next.
But I do like the underlying idea behind this provision. It corrects what I consider to be an error in all previous copyleft licenses, an error that has had very troubling ethical consequences. You're right that another way to correct it is to encourage non-copyright-assignment/non-CLA copyleft project legal governance. However, I don't want this license to be tainted by that practice the way earlier/existing copyleft licenses have been. I feel quite strongly about this; you're not wrong to describe this provision as 'opinionated' in nature.