We know that Assange coordinated with the Trump campaign to time the release of information dumps to maximize the benefit to Trump and harm to Clinton.
We know that Assange lied about the source of documents Wikileaks got from Russian hackers and intentionally fueled false conspiracy theories about Seth Rich’s involvement and subsequent murder.
We can clearly infer that Assange wasn’t interested in holding Trump or his administration to account for their actions, because Wikileaks has been one of the only journalistic* organizations on Earth that HASN’T unearthed anything on Trump over the past four years.
So yeah, please forgive me if I don’t rush to the conclusion that Assange turned down a deal from Trump because he was just too darn ethical to compromise his journalistic integrity.
As unsurprising as it would be if Trump made such an offer, I doubt that he would go through Rohrabacher for this kind of thing (Rohrabacher is not family, after all). Rohrabacher was probably there as an agent of Russia, rather than Trump. Then again, so was Assange.