i agree with you that there is a big difference between feeding live while taking the precaution to stand by and watch for any problems that may arise, rather then just leaving it in there and walking away.
But even that split second or longer (that are reflexes cant react too) is long enough for a rodent to take out an eye, or give your snake a severe puncture wound.
And then theres the time of having to intervene like marisa said, which can be a hard task for the even an experienced herper to get a hungry snake, acting on instinct, not pain away from a very scared rodent with sharp teeth.
I had this happen once , and i didn't even notice the snake had been bitten in the neck as it was coiled around the mouse in an awkward position that left the head of the rodent out of sight.
It wasn;t till i saw blood on the paper towel till i new something was wrong.
Since that day, i have starved a few snakes in my time of keeping snakes. and sooner or later they all came around.
Zoe, do what you can to get your friend to switch to frozen thawed. But i have noticed there are ppl that you just cant change there minds when it comes to certain ways they go about taking care of there herps. Try the feeding idea mentioned above, send him the pics, and if that doesn't work, let him/her learn on his own and hope that he doesn't learn by having an animal die in his care.
Grant van Gameren