From a game theory standpoint, this isn't always the case. The best example I can think of is tournament poker vs. cash game poker. If you have an edge in cash, even if it's thin, you're always going to press it. But in tournament poker, the value of preserving your tournament life sometimes outweighs the potential gain of pressing your thin edge.
If I'm trying to apply that here - perhaps some of the other variables outweighed - like the desire to not expose their 2 point plays, a potential injury to a key player, etc.
I would be interested to hear Tomlin's logic.