Sometimes when pulling the knife from a shirt or pants pocket the "flipper" will activate causing the blade to paritially open -
Thereby cutting/poking/slicing either the clothing material or one's neck or face if you're whipping it out without much thought to do this, that, or the other thing.
Doesn't happen much I suspect, but enough that they don't want the liability. However, if you know something is potentially dangerous in this fashion it - anymore - isn't enough to simply stamp a disclaimer on it.
Know your gear and wear / use it accordinly and you will have few problems.
GW