I think the logic is something like "Diana is supporting the Confederation; the Confederation is evil; therefore, Diana is also evil." But there's a difference between the Confederation and Hucksteen/the Deathly Regiment--Diana's not supporting the Deathly Regiment, she's trying to stop a mass-murdering terrorist. (It is possible she'll later be outed as a Deathly Regiment supporter, but I kind of doubt it.)