That's shit.
If you're talking on the phone while driving and fuck up because you're on the phone, it's not because you're holding the phone, it's because you're giving the conversation some of your concentration and focus that should be reserved for driving. Anybody who fucks up because they ARE holding a phone, should never take their hands off the wheel. They probably shouldn't even be driving.
No offense to one-handed individuals. This statement wasn't meant for you.