If you send your public servants to places like Iraq and Afghanistan, isn't it a bit of an impertinenece telling them what their state of mind has to be as they risk their lives on patrol or in battle.

Presumably the gentleman in question knows that coming from the culture that we do, we have many inhibitions (thankfully) against taking life. However battles are not won without killing people.
It's his job to get the soldiers to overcome such inhibitions that they have.

I seem to remember seeing army unarmed combat manuals from the second world war, with similar injunctions to have no inhibitions about breaking the necks of Germans.

I am waiting for the actual debate about the war to begin - although actual debate about a war in progress is a bit bloody silly. Win it as much as you can, once the thing has started.

Instead we have thread after thread started by people going Oh Horace ain't it horrid? Yes war is bloody horrid. Next subject...?