That's a bad interpretation of the rule and it gives the offense an unfair advantage. Technically, the defender is making a play on the ball by putting his hands up. He's not putting hands on the receiver. The receiver is running into the defender, not the other way around.
NFL refs will tell you they consider the momentum of the player as well. Yes, the GB receiver turned around, but his momentum was still taking him down field. If the receiver had actually changed momentum to come back for the ball and the defender STILL ran through him, then it would surely be DPI.
Ultimately, the spirit of the rules is to prevent an unfair advantage. It's something I always harp on when talking about NFL rules because they often are so vague.
Refs should be asking themselves "who has the unfair advantage here" and making (or not making) the call based on that.