I've heard a lot of people say this but I don't really agree with it. In that situation, your primary read should be dictated by the coverage. The #1 goal, in that situation, is to make positive yards and set up a manageable 3rd down. Pre Snap read tells Romo that the Safeties are in a two deep shell. Once the ball is snapped, he should read the LB drops across the board. There is literally nobody there to cover Murray and he really should know this. I can understand that what he saw was what could be described as open in the NFL with Escobar but that's not really the most open play. To be honest, Witten, IMO is a better throw then Escobar is. If you throw to Witten, you are throwing to the sideline where only Witten can catch it and he is as open as is Escobar. Also, he's not a Rookie. Having said that, pre snap, the coverage dictates Murray and Romo has to know that. Based on the down and distance and the situation on the field, I just think you have to go to the safest play because if it's not complete, at best you have 3rd and 16 and then you know you get the house. That's going to be a 7 to 10 yard completion at best and then your giving a short field to an Offense you know you haven't stopped once all day and all they need is a FG.
I think you have to understand that in that situation but hey, it's easy for me to post this on a board after the fact. It's a lot harder to do in real time of course but that is what your Franchise QB is supposed to do.