You should thank him--he's just preparing you for when Bean can do the same.
They do make "baby locks" for lever handles, by the way. But they suck. I've seen more than one kid defeat them in under 30 seconds. The knob covers for round knobs are pretty effective, though. At least for dogs. Extremely intrepid children may figure out how to rip them in half, but supergluing the halves together should prevent that.
But when you really, really need the door to stay shut,
this is the king of all door locks. Trust me.