Just to add to the comments already posted...The purpose of running on the hose is to clean out the cooling system or to allow the engine to run for a short time if you have a problem. It is recommended that you let the engine idle while on the hose, and not run it for more than 5 minutes at idle or the jet pump bearings and seals get over heated. The garden hose will only allow so much water to cool the engine, so over revving is gonna cause a over heat condition too as it starves for water. The jet pump is cooled by the water when you ride it. The rev limiter protects the engine from over revving to prevent engine damage.
Karl