Not following, Señor.
The line drive rule seems to be analogous, but I don't really think it is. On a line drive, the umpire has to judge that the ball was dropped purposely, whereas on an infield fly the batter is out no matter what the fielder does, purposely or not. And on a line drive, a fielder must actually touch the ball, because if he doesn't, it would wind up in the outfield, and in that case the defense couldn't (normally) get two outs by confusing the runners, right? Again, on a popup, the batter's out. The fielder's intention doesn't matter.
Sure, the sole purpose of the IFR is to protect the offense. But why should that change if it's a bunt? Why should the defense get an advantage because the popup was caused by a bunt, rather than a swing?