I agree that the lawyer’s letter being fake is equally plausible as someone leaning on the law firm not to sue CNN (as in: not remotely).
As is the possibility that the Senate Committee rejected a deal that they were never offered because the letter making the offer was forged and the whole testimony-for-immunity offer is fake news and never happened. 😉
There are many ways to see it … hence the word “theory”.
I think you’re missing a word in front of “theory” though.