Bunch of crap.
- Google already has a closed source "version of Android". It's the version of Android all your phones run which is based on AOSP + vendor blobs/patches + Google apps/services.
- Vendors using a closed AOSP wouldn't make them anymore willing to release security updates. The issue for google is that they can't create their own updates because devices need patches and blobs from the vendors. Whether the base of Android is open or closed means nothing to vendors. If they don't want to make their shit work with the latest release or backport security patches into their tree and fire out an OTA then it doesn't matter what license they got the source under.