As seen in the revert in https://gerrit.wikimedia.org/r/c/mediawiki/extensions/OATHAuth/+/772464, there is quite a lot of code that depends on things like property_exists and checking for SQL columns that may or may not exist.
We don't need to do this at runtime (ie during a normal MW request/OATHAuth auth flow). There are updaters (run via update.php) that should be taking care of that migration, and WMF production has been migrated a long time ago.
The Update scripts and any code they directly call would need to stay, other usages do not.