Well, if LVS has to be run independently on the macro and then on the global design (and just seeing the macro as an opaque block), that's fine. It was more about being as little disruptive of the "normal flow" as possible. (so that it's not viewed as a big obstacle, and really the inner routing of that macro would very local so hopefully only never reach met4/met5 and so the router would be free to still use those layer to route "above" the macro). But I guess the LEF specifies the obstacles and so it would know those layers are free and can be used for routing above the macro.