Not sure at what point you are referring to.
You are down 15. Score a TD. Okay that is what we are talking about. Now you are down 9 points. What do you do? You need a second TD no matter what, down 7, 8 or 9. My point is once you blow it by missing the first two point conversion you are dead in the water. Down 9 so you need to get the ball back twice, not once, twice. The odds of recovering two onside kicks is astronomically low. Ball game. I guess that is what the analytics say because it must assume the odds are you make that first two point conversion otherwise it obviously is the wrong strategy. So, of course, if you think the odds are good that you make the first two point conversion then do that. The odds would be the same with a 2pt conversion after the second TD.
I am also assuming there is not enough time after the second TD to get the ball again if you miss that second 2pt conversion. Do or die at that point.