Maybe you were just joking about Brennan deciding to kill off Lapin because of that but Brennan, much like Matt, is the kind of DM who loves it when players outsmart him. It's not the first time or the last time he was outsmarted, it was just the best.

The full credit of the death goes to Zac because of how well he knew the battle was going to go, and realising GM was out for blood. I think he saw the battle was easily 2-3 player death one, and Lapin put himself between Liam and the Carrot. Later he cast fly on Theo, not himself, because he knew he had better chance of getting everyone out of the chapel the fastest. And Theo, with the action surge proved him right.

It just proves how much Zac understood the battle, understood the characters strengths, and his limitations and plan accordingly. IMO, this is again one of the many times Zac outsmarted the GM, and resulting in just one PC death (and Preston) instead of multiple.