I can't help thinking that the dealer is trying it on in suggesting removing one of the casings to clean it out. All that is needed is to give the bike a good fast run, get it nice and hot and then drain the oil. If your commute is only a few miles and the bike is not getting hot enough to dry the condensation out then giving it a good hard run once a week should do the trick. It also might be wise to change the oil a bit more frequently, say at 2,000 mile intervals to reduce the risk of the build up of combustion products.