I dislike this change, ownership of an object is completely independent of the grant system of privileges. The granted privileges of the old row do not transfer to the new owner when alter ... owner to is executed. The separate object attribute "owner" is the only thing that changes. If the old owner doesn't have any granted privileges on the modified object then they will be left with no ability to interact with that object. In the case of Database the applicable interactions are Create and Connect. The permissions the old owner may have on any other objects in the database are also left unaffected - such as those on a schema. But if they have lost the ability to Connect then actually exercising schema privileges becomes impossible. It really isn't any different than removing their login attribute.
Note that since PUBLIC gets connect privileges on all databases by default...
David J.