My memory, sorry it has been a while, seems to say that the guild is trying to drive good people and adventurers away from the city, and draw in the less reputable ones, IIRC because the city is kind of doomed due to something with regards to the labyrinth, and they want those of value to society gone and safe from that doom.
IIRC the city is designed so it is easy to enter, but hard to leave, to protect the outside from something within, as opposed to the normal defend the city from outside threats.