First off, what's wrong with manufacturing weapons? The reality of the world today is that weapons are still necessary. In fact it's highly unlikely that weapons will ever be completely unnecessary.
Second, since when does the act of not manufacturing weapons become an excuse for immoral behaviour? I'm pretty sure if I came home and said "Hey Hon, I banged some hookers on my way home but at least I didn't manufacture any weapons!" I'd still end up homeless.
What an assinine comment, insightful my ass.