What problems might Atticus’s rule--“You mind Jem whenever he can make you” (Lee 138)--cause in To Kill a Mockingbird?

This was probably not Atticus' best parenting moment in
To Kill a Mockingbird. Although he was probably only
half-serious--he "smiled" when he made the comment--it does seem that he was advocating
the possible continuation of fisticuffs between his two children. His answer to Scout's
question--"I don't have to mind him now, do I?"--seemed to point
out that Scout was the youngest of the family and also last in the pecking order (behind
Atticus, Alexandra, Calpurnia and, now, Jem). But Atticus was a wily attorney, so
perhaps he knew that this would somehow unite his two children rather than cause more
friction. And that's just what happened. When Alexandra argued with Atticus, Jem and
Scout found the one thing they could agree upon: Their dislike of their
aunt.