I haven't thought this till somewhat recently, but it seems they stopped trying to make a good show and are trying to "throw off" the audience instead thinking it makes for good drama since they know how much this show is talked about on Talking Dead and social media, and numerous online articles.
I still have not watched this last episode other than the last 10 minutes, but honestly, that scene was great. JDM was great. He actually came close to living up to the hype of the whole thing. The lineup was great. It was set up to be great. Everything about it was great except the obvious. This was the barn scene without Sophia. Excellent scene in every way but without the payoff.
It just doesn't make sense to end it that way because 1, it is dumb and ruined what should have topped off a great scene, and 2, the person he killed is going to be KNOWN before the first episode next season. Guaranteed.