Why did he have to touch the defender, i mean why was the defender hanging onto him? Your not allowed to do that after 5 yards. If you don't call the defensive holding you shouldn't call the push-off, especially when the push-off wasn't needed for the separation
I'll try to make it easier for you by highlighting the applicable rules.
Actions that do not constitute pass interference include but are not limited to:(a) Incidental contact by a defender’s hands, arms, or body when both players are competing for the ball, or neither player is looking for the ball. If there is any question whether contact is incidental, the ruling shall be no interference.
(b) Inadvertent tangling of feet when both players are playing the ball or neither player is playing the ball.
(c) Contact that would normally be considered pass interference, but the pass is clearly uncatchable by the involved players.
(d) Laying a hand on a receiver that does not restrict the receiver in an attempt to make a play on the ball.
(e) Contact by a defender who has gained position on a receiver in an attempt to catch the ball.
Actions that constitute offensive pass interference include but are not limited to:
(a) Blocking downfield by an offensive player prior to the ball being touched.
(b) Initiating contact with a defender by shoving or pushing off thus creating a separation in an attempt to catch a pass.
(c) Driving through a defender who has established a position on the field.
And I agree the push wasn't "necessary" --- he had position. But he pushed anyway and it was stupid, especially knowing that on that play, the back judge was on ten feet behind him and couldn't possibly miss it.
Don't be mad at the official who made the correct call. Be pissed at the player who committed a stupid, needless penalty that cost his team 6 points.