As long as you see a bit of effort, you (as a ref) usually give the bottom guy some leeway. Grosso did go down on one knee and speak to him, which I was suspect was him telling to improve (basically a ref warning that you either show some effort or I'm going to hit you with a stall call).
From my perspective, Grosso called that correctly. As I said in my post, Davis needed a couple of cleaner shots in the 3rd to make it clear that Bailey wasn't doing anything. Instead, he took some poor shots that Bailey could block with little effort, and without backing up.