By not getting involved with alternate Iris and Joe. If he had just gone to the police station and got the information they had about Zoom attacks as he planned, Killer Frost and Deathstorm would have attacked the club looking for a breacher because he was there. Alternate Joe would still be alive and alternate Lawton would still be alive. But instead, he just went full-on wish fulfillment and wasted 24 hours of the 48 he planned to spend on Earth 2.
How the hell could it be considered all good? How could kidnapping your doppelganger, living his life and then having the audacity of saying of his family that they are your family and have to protect them (all the while you are the reason they are in danger) be anything else than completely retarded?
In this episode, Zoom did more to advance the plot by putting Barry in a cage next to Jesse than Barry himself.