ding ding, you're correct on predicting what will happen next based on what i read in the WN
however the thief is actually just a good kid who happen to end in a bad group and its the doofus job to bring the good kid into the mc side (and doing ridiculous thieving skill that make me say wut
)
based on the WN, the doofus only got his comeuppance at the end of the arc, which im sure its going to take quite awhile