Shaving

Question

Why must JOe explain clearly to you why he thinks that it's prohibited to shave (during chol hamoed) inorder for you to tell him the heter? JOe's reasoning is irrelevant to the svara for the heter (I don't know JOe, so I don't mean JOe per se, but an individual such as Joe can be an ignoramous and just be asking for no other reason than he sees other ppl not shaving. Lets say this is his reasoning what would your response be? Or lets say his reasoning is that he learned through the mishna on (moed katan 13b) and saw that the mishna lists those ppl that are allowed (ie; beis shivya, yotzei Mbeis Hasurin etc.) and that its assur for others because of the takkana of the rabbis, which was made inorder to motivate ppl to groom themselves prior to yuntif, so that they didn't enter unkempt. and after learning the mishna, he wanted to look at the halacha L'maseh so he went o look it up in the Shulchan Aruch, and saw that the Shulchan Aruch poskins that one is not allowed to shave. I haven't looked it up in a while but if I'm not mistaken he says even if you shaved erev yuntif it's still assur during the moed. In this scenario what would your reply to Joe be?