Man, those guys are dumb. Also how weak are the adventurers in town that they go to the slums and die.
Though maybe that's just some stereotype. Touya wasn't attacked until he helped a kid in town. Everyone else in the slum left him alone.
Also realistically speaking, the orphanage being taken care of by the guild would be bad, wouldn't it? Won't the guild want the children to work for them in order to pay back the money they used for the orphanage? (Just my own thoughts. Doubt the story will ever go that far or show anything in that direction.)