If you can demonstrate the ability to land at a reasonable forward speed with the skids pointed in the right direction, why not practice and demonstrate that skill on the safest, most forgiving surface possible? There is nothing gained by demonstrating it to grass.
Grass is a safe and forgiving surface and is at least a better representation of what you might have to deal with in the real case.
If you let people only demonstrate their skill on a surface which lets you get away with sloppy heading control you are ticking a training box rather than keeping up to a standard (sadly something all too common nowadays).
The fact that instructors and inspectors struggle is exactly what I mean by dumbing down training.
The widespread use of Robinsons and their lack of suitability as a training machine (due to number of accidents) has driven down training standards in the industry as a whole - well done Frank!