I remember that episode, it was very good.
That ending actually didn't bother me because, if I remember correctly, it seemed the story was more about the situation and attitudes involved, and less about "whodunit". It didn't really matter who was or was not at fault, it was more of a character/situation study. It sort of left it to you to decide who you
wanted to be at fault, if you know what I mean.
That said, I am actually something of a fan of open-ended stories. It's great to have a nice satifying conclusion, but if it's done well an "un"-ending can be just as fulfilling. It lets me use my imagination and continue the story in my head.
I read lots of short stories when I was younger, and that seems to be a pretty common technique in many of them, especially science fiction and horror.
But then, YMMV.

(Your Milage May Vary)