Your argument amounts to: "Before X happened, and after X had stopped happening, X wasn't happening".
Logically it's very strong. It's also neither here, nor there.
The "extinguish" part refers to the transition from Linux on mobile being a thing thanks to Android (on billions of devices) to Linux on mobile not being a thing anymore (or being a small niche) in a post-Android/Fucscia world.
It doesn't matter if Linux on mobile wasn't a thing before Android, the same way when defending a murder "Well, the victim wasn't alive before it was born either, judge" is not an argument.
They aren't going to be interested in supporting Linux after Android.
Google hasn't extinguished anything. Linux just didn't offer a compelling reason for companies to support it.