I have trouble believing that, since I typed the phrase, "rational proof for the non-aggression principal" into Google and the very first link was the book that I would recommend on the topic. So it's not like such proof is difficult to find at all for anyone who is truly interested in the subject.

I don't provide links any more because almost always what happens is that someone will declare a desire for a rational argument and when shown one will reply with, "I don't like it" instead of a logical refutation.