Then rather than engaging in an emotional battle, read the content of his statements and judge their veracity as an idea separate from the man. If motive is impossible to discern from the data you have, you need more data, right? At least if you know what it is that he is accusing the govt of, specifically, will help to determine more of the motivations behind his choice, right?

I’m not saying read them and believe them, but rather cast your critical eye upon his focus, and then perhaps you can poke holes in his conclusions or discern what, if he’s lying, those lies are meant to achieve