It is completely possible to make whatever point you want to make without using a character as a prop.
“Two characters have a conversation where one is a strawman who is clearly wrong and the other is my mouthpiece who is clearly right” != “Show, don’t tell.”
That’s just telling with extra steps! Also, it is baby-level storytelling! Wouldn’t you rather be writing something with more emotional depth than a goddamn episode of Mickey Mouse Clubhouse*?
Not to mention that, given your chosen profession, you literally have the capability to show instead of tell. Do you know how much depth of meaning can be conveyed through art?
A LOT! You don’t need a fuckin speech bubble of some jackass going “and that makes me feel angry!” when I am looking at a panel that is clearly conveying “this character is angry!”
Art and words are supposed to flow together in sequential art, it’s not just “words are for plot and art is for flashy splash pages!” JFC.
*—this is not a knock on baby-storytelling or Mickey Mouse Clubhouse. Babies need stories too!