I'm a father (and I also remember something about being a kid) and I can tell you that 4 year old kids are unbelievably egocentric. A lot of the rules adults try to impose that are perfectly reasonable to anyone with enough empathy seem completely arbitrary to a 4 year old. So, "don't yell because that distracts/bothers me" is an "arbitrary" rule coming from a "cranky" dad. "I put a script in the machine that will shut down the screen if you yell too loud" gets translated into "I don't want you to yell", which is, again, an "arbitrary" rule kids don't care about.
On the other hand, "computer doesn't like loud sounds" is a perfectly "reasonable" rule, because the computer is "in charge" of letting you play the game. You disturb the computer, the computer reacts. And you can't argue with it or try to manipulate it. Crying at it or throwing a temper tantrum won't do any good. It has no mouth, so you can't have a conversation with it. In short, you have to follow its rules.
If you want to avoid having the kids jump to the "logical" conclusion that the machine is a person, you can formulate it differently: instead of saying "the computer doesn't like loud sounds", you can say "the computer is a machine that doesn't work well when there's a lot of yelling".
Then again, someone else already pointed out that kids believe that an old, fat man can come down their chimney and leave gifts in a matter of minutes -- and do so for every kid in the freaking world -- without suffering any psychological scars from an "untruthful" method of influencing their behavior (because Santa brings gifts only to kids who are "good"), so I don't see what the big deal is with going through a short period of believing the machine is a person.