I'll rephrase - because the referee judged that there wasn't contact, it was an indirect free kick. I was responding to the rules of the game aspect, not the specific incident. The referee upheld the correct rule under his opinion of the incident.
Correct decision. He didn't foul Knockhaert - there was no contact. If there had been contact, he would've given a penalty.
Instead he gave an indirect free kick for dangerous play, the defender going in with his boot too high...