The only hope is to eventually change the default, so probably the best thing is to apply pressure via the SQL Std process.
Then there is no hope because this makes the situation worse.
If anything I'd suggest the SQL standard should probably just admit this "default behavior of timestamp" is a bad idea and deprecate its existence. IOW, the only two standard conforming syntaxes are the explicit WITH/WITHOUT TIME ZONE ones. Any database implementation that implements "timestamp" as a type alias is doing so in an implementation dependent way. Code that wants to be SQL standard conforming portable needs to use the explicit types.
