I think you and Mori have gotten into a different conversation than where it started.
I don't think he was originally arguing against tagging or signing Melton. Just against as specific comment about HAVING to tag/sign him, and that. Sing related to him being a homegrown player on the upswing. HAVING - as in, no brainer.
Now, if I am right in that then I agree with both of you. It is NOT a no brainer because we have lots of needs, and a new coach who may someday implement a different scheme where Melton wouldn't fit as well.
Simultaneously, I strongly believe that tagging him (and signing him long term if they can at a reasonable, maybe slightly less than free-agent market value) is the right decision. Because he is a very good, maybe elite DT.