IMHO the best procedure in this case, as valuable as the content of the messages might be (and I think both messages were very good, very important, is to remove that content.
The nature of a Great Debate is meant to be a limited discussion betwen two individuals. Additional input, no matter how good, no matter how much it adds to the content, is not appropriate.
However, in this case a moderator has already stepped in and made a decision and Mark24 has responded and said he would not post further. I would let this one stand as is.