It means, unless you are a good contact hitter, ala Ted Williams, it isn't a good idea to take a good pitch to hit on the first pitch. You're going to hit about the same when you put the ball in play so if you get a good pitch to hit on the first pitch, go right ahead because you'll never strike out when you put the first pitch in play.
I used that study on here to show why it did pay to take on 3-0 in most but not all situations.
For example, needing one run to win a game with a runner on third you might go ahead and swing at a good pitch. Walking in that situation increases the probability of scoring multiple runs but doesn't necessarily increase your chances of scoring just the one run you need by much.