It's analogous to coming up with one counterexample to disprove something in mathematics.
I can reasonably theorize that he fully intended to stop bombing people based on this "deal". There. Done. I can doubt he planned to bomb people in a reasonable way.
The onus is on you to remove all reasonable doubt. You have not done so by simply showing that there are bombs in his cabin. He could have built them before he made the deal to stop bombing people. That's a completely reasonable scenario.