There are no OWE restrictions that I know. Lots of us break RTWs and return home on separate tickets.

BA N class earns 25% on AA, except transatlantic travel to/from the US on any class, that earns nothing.

Edited to add: I suppose a case could be made that returning to the point of origin (on a separate ticket) before 10 days would break the minimum stay rule, but I doubt that is being enforced, or checked.