Although you don't have to catch the ball on an infield fly, the results of the fly ball are still in play, so if the ball hits the ground it could allow the base runners to advance, so catching the fly ball or at least making a play on it still matters.
The problem is with the interference rule itself requiring an automatic out of the player interfering. There should be some leeway there for the umpires to make a judgment call. The interference here, which by the way was a truly terrible interference call, did not reasonably change anything because the play was made as expected and nobody advanced on a play that nobody was going to advance on anyway. There's no reason to call the runner out.