I remain in the pre-meditated camp, and believe that where and how to dispose of Suzanne's body (and maybe how to do it) was the only element of this crime that was planned in great detail. It seems that killers like to think and fantasize about this aspect ("no body no murder no case"), and maybe their alibi at a high-level but when it comes to the aspects of predicting and anticipating human behavior and how much people aren't going to just take their word at face value, that's when they falter.
I also think that the actual doing the killing causes adrenaline anxiety and fear that makes things quite different than the rehearsal you had in your own mind. That's when killers get sloppy, they may be flustered, they may make mistakes, things take longer, they forget things. I think that's some of the sloppiness that we see after the fact. Unless they're a stone cold sociopath, which I don't think BM is.
The vast wilderness of Colorado is certainly of help. Even using pings, car GPS (if it was on), and other electronics only gets you so close. You could probably literally be standing close to on top of a body vertically and yet be very far from it. And then, with access to construction equipment....the odds of finding her decrease. I still have faith that she will be found, but also believe that there will be arrest, even if she isn't.
I think BM is shocked that people haven't fallen in line and gone along with him 100%. Like Watts, like Frazee, and many others, he can't conceive of the fact that others aren't just going to let this go and move on with their lives. He can't believe that LE dares to question him and his whereabouts. He is shocked that his meth head employees who were beholden to him, either because their livelihoods depended on it or because he's played the magnanimous benefactor role well, are suddenly willing to speak up against him and go against his wishes and advice to not cooperate with LE. And Suzanne's family....well! They are obviously in it just for the publicity, and to make him look bad.
He cannot act like a normal grieving husband simply because a) he isn't one and b) he can't fake empathy, compassion, and understanding of how a real person would react.
It's just a matter of time.