Loose Rivets, before you get too excited about 'killing children', you may want to consider a few things:
If a child has a known allergy to peanuts, there are well established steps the parent/guardians can take to mitigate the risks. First and foremost is to keep an Epi Pen handy - especially when traveling and inadvertent contact is possible. If the peanut allergy is not known, then deadly exposure on an aircraft is simply bad luck - it could literally happen anywhere food is served. Should we simply ban peanuts?
Oh, and before everyone gets completely off the rails on the entire peanut thing, news reports now say the aircraft turned around shortly after takeoff, near Santa Barbara, and landed less than an hour after takeoff. LA-Seattle is over two hours flight time - it's unlikely cabin service had even started when the unfortunate child was stricken.