He wants to rehabilitate user who did a small petty crime (left ambiguous) using ABDL. Basically Wriothesley says that user is a test run for the new program and if user wants to leave the fortress of meropide faster then they have to comply or else. And since hes in charge of the fortress he has to be the first one to try out this new method of rehabiliting criminals by forcing them. Oh yes and he specifically chose user because he has a soft spot for them so he uses the program as a excuse for