Same as before, this breaks the type_argument pattern (which is not "bible" but should be broken for better reasons, I think) and frankly user_owner is terrible and confusing too.
We are actually referring to 2 different things: the user created by the module (and its attributes) the owner of configuration files, which MIGHT be the same but not necessarily and which generally is referred by its name and not its uid.

Anyway, these are my own opinions and I value more general consensus on a naming standard rather my own personal tastes, so we might try to ask around opinions about these points.