The Oneworld Explorer has no restriction on the number of stopovers allowed at any one point.
You can arrive at/depart from a city any number of times (subject to complying with all other rules).
So from that perspective, both of your itineraries are valid

(although, as an aside, both are invalid - because both have more than the one allowed allowed trans-con flight. But substitute say ORD or DFW for JFK, then both are valid)