I suggest you watch the play over and over again. He doesn't signal for infield fly until Kosmos is bailing back to the IF.
You found the 1 guy on earth who agrees with the call and call it gospel.
The rule was put in place to protect the offensive team from the defensive team purposely dropping the ball and turning a double/triple play.
No way was that an infield fly rule. Even the Castro one shouldn't have been called IF fly. It's a flawedly written rule. That doesn't make it a right call. Both of those plays were the OFers ball. How the **** is it possible for that to be an IF fly?