The OEMs will just add the uninstallable flag functionality back because Android is open source.
The only way to prevent OEMs from doing that is to tie it to the Google Play Services agreement which will, again, open Google up to yet another antitrust suit.
If this is the case legally, then it seems in the world of phones, an OSS operating system puts users at the mercy of more organizations (OS developer and phone manufacturer) rather than giving them more control.
The only way to prevent OEMs from doing that is to tie it to the Google Play Services agreement which will, again, open Google up to yet another antitrust suit.