Yeah actually they don't want you to service it as most people do not have the equipment to charge a shock or remove the charge safely.
My manual says the same thing and so did my 05 GSXR1000 which was resprung and valved for my weight.
The big question is with a host of better more serviceable shocks on the market and used for a real good number would it be worth doing a stock shock anymore?
Manual also says to replace crush washer on oil drain but you know sometimes you just don't have one and have yet to drop a drip.