Danimal said:
Reilly wasn't watching what he was doing and got away with one. He was not forced out of bounds. You can't be forced out of bounds by a defender that has his back to you that is running downfield.
No. You're wrong.
Your premise is that a DB can't ever be guilty of interference in any way if he's looking back at the ball, with his back to the receiver. I know you didn't say that explicitly, but that seems to be what you're implying. And this is absolutely, 100% not true. There can be such contact on pass interference calls, and it can apply to this case as well.
And on the replay, he straightens his arm behind his back to make contact with Reilly. The hat comes off. The ref sees the contact with the straight arm. The call is ruled as simply contact by the defensive player. They review it. They confirm contact. Correct call on the field upheld.