"You weren't there, so how would you know?" is the common way to shut up an argument by an opponenet. There are many examples: Chickenhawks, neo-cons, etc. However, here is someone who has been there twice, and is there right now.
You cannot dismiss it out of hand, because his presence ensures his credibility to a greater degree than any other argument can.
Before we surrender, let's listen to those who are there. The fact that he is an NCO and not an officer seems to extend his credibility, since he is less likely to be politically correct, but speak the truth as he knows it.
Give it a read.