On the Felucca facet players will walk through other mobiles if full stamina. On other facets you can always walk through other players and mobiles. This is by design.
I've not tested it but you will need to change Mobile.cs in the core to make it the way you want. Have a look at the CheckShove method in there and remove the MapRules.FreeMovement part and the if( Stam == StamMax ) part so that it always returns false.