Murray is so passive. Most would have won that shot, but he was probably counting on the error (from Novak) or the easy pass.
I think you're criminally underrating how difficult it is to execute that shot.
For starters, Murray played aggressively to get Novak in that position to begin with. Most players would have probably let the next ball bounce, and Murray took initiative in (mistakenly) doing otherwise.
I called it poor shot selection, but really, it was a high percentage aggressive shot. It was a much safer bet than playing it down the line, and Novak appeared down for the point anyway.
He did what he thought he had to do. There's no way he lost that point due to passivity.