Yes, you can totally do that. The problem arises in this line
With the ToDSType method you’re converting the grid from a revit grid to a dynamo grid and later when you call the Grid.Curve property, the result is the same as using the built-in “Grid.Curve” node and you get a dynamo line. If you remove the the whole line or at least the “.ToDSType(True)”, the grid creation should go through.