What do you think that would have proven? That you can hurt yourself? That disk doesn't hold your SOUL. That disk will never hold your SOUL, because you are a monster, and if you have a SOUL to find, it's inside your body!!

[Mettaton can't look at Asriel, but the way he angles his head up, and the way he's speaking? It's clearly indicative of how upset he is. How could Asriel ever think to do something so potentially destructive.]

And even if it did migrate to that disk, if you broke it then your SOUL would shatter, and that would have been the end of it, don't you understand?! We can't be brought back anymore!! Why would you risk it? Why would you hurt yourself like that?!