Because it is only a fast idle, I.e. Opening the throttle bodies and injecting additional fuel I can't see how it would cause any issues using it as I do, the worst I can see happening is decreased fuel mileage and slightly higher temps at the exhaust.
There is a camp that believes no modern vehicle should be armed at a sit-still because the EFI mapping tends to be overly rich for cold start and cold run rpm tends to be highy (partly in an attempt to get the 02 sensor up to temp for closed-loop operation).
The fear is that the overly rich mixture tends to wash down oil from the cylinder walls and/or lead to extra contamination/dillution of the oil.
So the recommendation is that if you ride/drive the vehicle lightly during warm-up it will reduce the amount of time it spends operating in an overly-rich condition.
They (whomever they are) say don't ride with the fast idle lever on because as the bike warms fast idle increases. If you forget to turn the fast idle off while riding you can find yourself in a potentially dangerous situation since the throttle won't go down to idle speed when released. Real issue? Up to you.
Sounds like complete crap to me.
