According to the article, the main difference between GPLv2 and GPLv3 is that having the Secure Boot unlocking process wipe the disk, and therefore destroy the proprietary software installation is kosher under the GPLv2, while v3 requires the proprietary software needs to continue working.

I would argue v2 is even better, because it forces unlocked phones to use alternatives to Android (that is, the proprietary Google Servics), like Lineage, while avoiding turning billions of phones into bricks.