Maybe you did this too: I misread the comment you're replying to as

> …you’re arguing against someone who believes they are.

when actually it says

> …you’re arguing against who someone believes they are.

(meaning “you're arguing with someone against who they believe themselves to be” or something like that.)

I would have rather said he was arguing with who you about who you each think you can be. That is different. The question is whether or not you think you can remain a genuine and caring person while being a politician.