That implies that there are people to whom this treatment would be appropriate, effectively saying that it's OK to dehumanise some people but not others. That's not true. It's not OK to dehumanise anyone, ever, regardless of what they're accused of or even what it's been proven that they've done. Dehumanising behaviour not only affects the victim but the whole of society. Living in a culture that deems it normal to treat other human beings badly changes the way that everyone thinks.
There is a one-size-fits-all approach: Treat everyone well.