viz.

Anthony Lane's article for The New Yorker pointed out the same thing as your son did. Only he seems to smirk at the movie (and current Disney) for lacking "the seriously bad guys and the top-grade sidekicks" of previous films like The Jungle Book. It was a really odd moment. 

[Spoiler alert]

Now that you mention it, though, it's interesting that there are in fact two villains, of sorts, who certainly receive no love at the film's conclusion (but who also aren't killed.) Both are lying men seeking to exploit the realm for their own good (one wants to kill Elsa so he can restore his trade agreements, the other wanst to kill Elsa and Anna so he can seize direct political control.) As someone increasingly disturbed at our nation's foreign policy over the last decade or so, I'm particularly intrigued by the squeaky Duke of Weselton played by Alan Tudyk. His devotion to regional stability, and his willingness to remotely command the death of a possibly-innocent figure if she poses a threat to his national interests, makes him an odd reflection of our nation's own checkered history of intervening in other nation's politics.