It wasn't an edgy decision, it was a bad one. It removed agency and option and got a player briefly involved in a bad situation they were intended to fail at just so the DM could make a point. There are other ways to do it like just have you make a perception check and see this happen across the way, otherwise you see a dead body and need to ask someone so they tell you who did it otherwise a snake did..

As a DM, if the argument is narrative and mechanics, they did a piss poor job of it and I could spend all day writing down more interesting things that could happen that the players could be involved in that also drove home the fact that choices matter. Making choices matter and then restricting their ability to choose and act is a dick move.

Can I justify what they did? Yes. I can actually justify just about anything. The question is what is the best way to do that and I cannot imagine a scenario where I would end up choosing what they did.

What is the problem you are solving? Does your proposed change solve the problem? Is your change feasible? What else will be affected by your change? Will your change impact revenue? Does your change align with the goals and strategies of the organizations (Larian, WotC)?