I as a layperson at least am not familiar with any concept of a nonhuman 'person' in law, though based on past discussions, I seem to recall it apparently exists in German, and possibly also in other formal legal language.
Think Citizens United, in which SCOTUS declared that "corporations are people, too" (that's possibly paraphrased, but their ruling was along that line). I don't think that US law typically makes a big distinction between "natural persons" and "juridical persons" (except for in Louisiana, apparently -- and the fact that corporations can't be thrown into prison), but, from my experience, it's common in European legal systems. I find the concept quite sensible, and it would have avoided to some degree the corporate takeover of the US electoral/campaign-finance process.
Since Mr. Carl is an actual individual, I suspect that "it" is being used here to avoid gender-specific language and is being used instead of "they" to make it clear the he is an individual. (Even though the "single they" is long established and is becoming more common, whoever chose to use "it" here may have wanted to avoid ambiguity.)