I don't think drooping the Nr at the end of an EOL to cushion the touchdown should be considered as operating outside RRPM limits - you have to learn to do EOLs somehow and you have effectively landed anyway.
Drooping the Nr in a low hover to show overpitching or TR effectiveness might technically be considered outside RRPM limits but is essential training for students to understand what it looks and feels like so they can recognise the symptoms early and recover quickly.
I am sure all of these techniques are taught on the Robinson safety courses so the manufacturers must be happy with them.