I'm impressed.
Someone has the capabilities to get into another's program and do damage.
I'm impressed with how short-sighted it is. If Matt doesn't build a routine to remove the additions, I will; one by one. My feelings about the issue and the person who did it will be just the same, only deeper. That's about as polite as I can put it.
Our democracy is founded on two (amoung others) fundamental principles - rights and responsibilites. It's obvious this behavior violates these principles.