If his back holds up, there are some guys that peak in their early 40s. Your back is pretty much the most important thing in golf, if it goes, your done. I don't think his back injury is anywhere near as bad as some life long golfers like Greg Norman, so he should be fine to play as he was probably more healthy to play football than some think.
With Romo's history, I wouldn't put anything past him to make some noise in golf. But, there is a big difference between being a scratch golfer and on tour though, alot of times people think golf is that easy.....its not. I always laughed when people thought Michael Jordan could just step into golf, hilarious really, but Romo is much better than Jordan at golf of course.
