Must and should express the necessity. Both "must" and "should" are axillary verbs. The term "should" is used to discuss duties, obligations and if something is right. We can also use it to do anything in a specific situation, specifically if judging someone's activities.
Come on now, you disagree at everything I say with minimal arguments if none. As for the developer, once again, they should not be demanded or treated like that. And clearly based on the down votes, gladly I am not the only one who disagrees.