They generally do whatever the devs feel like it doing at the time they write a RP etc. Generally it also depends a bit on how much efforts was put into RP'ing the whole thing, which at this point it seems nothing was done of that sort.
Yea, not placing "blame" on the devs. Though if the Zuma wanna squat Darfix from now on, killing rogues around them (but keeping within a few regions of the city), that's fine by me.
Or if the portal wants to send all nearby monsters straight to the Netherworld, that's also fine by me!