That's brilliant. Believe it or not, the worst injury we've ever had on our boat was on just such a cleat.
I took my mother out for a 3-day cruise. Our first night, we pulled into Friday Harbor after about a 10-hour stretch. So, everyone was anxious to get off the boat. My mom (against advice) tried to step up and over the coaming (one foot in the cockpit and the next all the way onto the dock). She misjudged just how far that step was and fell. As she fell, her calf was pulled across the cleat in such a way that the horn managed to push into the skin and under the fat layer. It ripped about a 6" hole in her leg.
You could try 1000 times to replicate the injury and never do it. But, somehow she managed .
So, I guess it isn't a bad idea to cover some cleats as a safety measure, too? It isn't a thing I would call a "hazard" but, there you go.