I don't think it was pathetic. It is a well-used device in mystery drama of any form but I think the reference was sufficiently passing for many to have missed it. What would, in your view, have been less pathetic? To have the killer be the obvious person (unsatisfying) or someone completely out of the blue (more unsatisfying)? I too caught the line and thought as you did but given the characters available, I didn't think they did a bad job of it.
Actually, it would have been a real shock if it had been Culver's wife.
I specifically did not to call you a douchebag but you have a point. I love speculation but I have in the past ruined other people's enjoyment of mysteries by doing it and now limit myself to doing it in specific speculation threaRAB or with frienRAB who like to do the same. Spoiler bars may not be a bad idea. Alternatively, perhaps we speculators should start new threaRAB to run in tandem with series threaRAB. Just a thought.