Hi Steve -
That might/will probably work on Rhino 7.
Here’s a Grasshopper solution as an alternative:
Only 2 components, it doesn’t get simpler than that:
You select your points in a Rhino viewport, right-click on the Pt component and pick “Set Multiple Points”:
Grasshopper then shows the solution in the Rhino viewport.
Select the C# component:
… and hit the Insert key on your keyboard.
That will add the ellipse to your Rhino document.
-wim