Thoughts on best practices for user content management
If nodes are supposed to match 1:1, why not to make them one node, with different displays and access to different fields?
Or, actually, if you have only one restaurant per owner and one owner per restaurant (and it looks like that, when you say that changing author works) you could define restaurant info as a set of fields at user's profile itself. That way each user would be able to edit his own data, and data of his restaurant, and you can use views to decide what to show and where.