Riding the clutch means holding it at the friction point and feathering it to make it slightly grab.
Meaning no disrespect to anyone, but if a rider is in a parking lot and the rider is going slow enough to have to pull the clutch (feather it) then the rider should stop to put distance between the rider and what ever is in front of the rider that is causing the rider to slow to a speed that is not safe for traveling. Driving that slow would almost mean you are walking the bike while in the saddle, easy to lose balance and lay the bike down. If a person is at a stop light or sign on a slight grade, where a lot of feathering of the clutch does takes place, then feathering will not hurt the clutch. Most MSF riding courses recommend that you come to a complete stop and hold the hand brake, feathering is still not recommended.