"Even as they released their premium Cyanogen OS ROM for devices with proprietary extensions, the CyanogenMod ROM still stayed 100% open source."
That wasn't their original plan - but they realized after the Focal mess that trying to leverage your CLA to obtain dual-licensing rights to a GPL application that was written by an opensource contributor was a bad idea PR-wise. (Fortunately, their CLA didn't actually legally allow them to do what they wanted, and even if they did, that application was forked into CM directly from github without going through Gerrit and hence the CLA.)
I wouldn't say that until now the Cyngn team are really cool. The core team (who founded Cyngn) at one point went by the name "Team Douche" - and since the founding of Cyngn they've been pretty regularly living up to that name. Cyngn will always tell you that CyanogenMod is separate, but the reality is - All but 1-2 of those who have global +2 rights on the opensource project are employees of Cyngn. This is a fundamental conflict of interest, and it's clear that when it comes to corporate vs. community interests, corporate always takes precedence (see Launchergate)