Tim, yes you can, and I have repeatedly. The issue is not can I spray over it, but should I.
The surface is great, not too many issues except for the folds. They pose problems, but not that you can not overcome.
I have also sprayed over exposed stone with a clear version of polyurea. Actually we are spraying a little project up northerly from here. Over the last few weeks almost 3800 gallons of polyurea. And they still need us to spray more within the next few weeks. Just can not do it under water
Photos of a small pond sprayed over the natural stone, and some larger stone on the larger project as well. the smaller pond would not hold water, it was an old concrete construction, they had tried different treatments including epoxy's, and all failed within two years. Without having to take out the stonework, we sprayed right over the top.
The larger stone is about the size of a tahoe, and has about 100 mils of polyurea on it.
When dry, and aged, it has a look of being wet, even when dry.