It's actually like this :

1.: 70(s) + lowbie enter instance, pull stuff back to zone entrance
2.: Pala kicks mage
3.: Pala weakens mobs <30% hp, runs out
3.: mage novas & finishes off mobs still unpartied
4.: Lowbie gets full exp
5.: Mage rejoins before timer kicks him out
6.: No profit because you don't loot anything while PLing.


And yes this also works, as long as your lowbies can actually finish the mobs off. (same technique as DoT & zone). No need to kick the 70 just zone out.
1.: 70 + lowbie(s) enter instance
2.: 70 weakens them/aoes them down to near-death
3.: 70 is kicked from party OR leaves instance
4.: Lowbie(s) finish off mobs?