I suppose i could be somewhat confrontational (gently so in this case) but if you didn't think about the consequences about Zack's choice then, why would you expect Braden to? Braden even specifically says it started out small. How many things in our lives start out as a small lie or stretch of the truth, only to continue to accumulate and become a leviathan of lies. At some point, we have to shut those down and the bigger the lie becomes, the harder it gets to shut down--or to even find a smooth way to shut it down.
There's also a ton of truth in how frustrated we can become with others when they essentially wrong us in the same way we do them. It could also be projection from Braden. To me, there's about a million reasons why Braden could react the way he did. It's a dilemma and because of that, it was avoided and it festered as most things that are avoided do and I wanted to show that things can fester with good people that originally had honest intentions. To me, that exchange is way more complex than just a comparison of who did what worse