It might have made more sense if the final scene had included action from the book, in which the "star-child" reaches out a finger (perhaps the finger was just a metaphor for some sort of thought-field) and detonates all the Earth-orbiting atomic weapons, one at a time.
Either (a) that was too much for Douglas Trumbull's special effects team to accomplish, or (b) Arthur Clarke added that detail to the accompanying book after the movie came out.
good to know. i just can’t read clarke.