Contact allowed within 1-2 yards of the LOS. It was man to man coverage and the DB covering the slot wasn't contacted and chose to go over the hump and not through it. why not go through it and force the refs hand? It was clear he wasn't going to be able to stop it going around the mess. Getting offensive PI was the only way to stop that play.
Also not sure who tackled who on the outside. DBs hands were on the outside of the receivers shoulder pads and the receiver was going down, depending on the ref's vantage point could have looked like DB pulled. Him down. Good no call.