The chances of not converting it were minimal, so that needs to be factored into the equation. Of course, the "minimal" happened, but that doesn't make it the wrong decision. Just like if you punted from the 50 to be "safe" and it ended up being blocked and returned for a TD. The chances of that happening are slim, and just because it happens doesn't make it the wrong call (it generally is the wrong call, but that's not what makes it as such). If the payoff was slim here, so was the probability of something going wrong. But, sometimes, poop happens.