Call me clueless but I really have no idea what this means.
indict Mueller for all his crimes.
If you combine this with the Corsi story, what you have is two of Mueller’s key witnesses refusing to submit - even at the risk of added prison time.
It suggests Mueller is trying to “squeeze water from a stone” - he is offering them plea deals if they give him dirt on Trump, but they have nothing to give because there simply is no dirt.
It suggests that Mueller a) truly believes Trump is guilty of something and that he can force testimonies from these witnesses, or b) knows Trump is innocent but is trying to extort these “witnesses” into making false testimony anyway.
The latter is less likely, but either way, Mueller appears to be in a weak position (assuming Trump is innocent, which I certainly do).
Put it this way: If Trump were guilty, there is no way these two would face lengthy prison terms to protect him - it would be stupid - why would they? For one thing, a guilty man doesn’t inspire that kind of loyalty. For another thing; if Trump were guilty, these two would assume the truth would “out” and that Mueller would eventually get his proof. Their lawyers, their families, would urge them to take the plea deals.
Consider the more likely alternative: Trump is innocent and these witnesses know it - they are being offered plea deals if they testify that he is guilty - but that would be perjury against a sitting POTUS, and therefore a VERY serious crime. Their lawyers and their families are urging them to reject the devil’s bargain.
It means that Mueller believes he has the evidence that Manifort broke his low sentence plea agreement by lying. Thus if Mueller can prove he is right, Manifort will face a longer prison sentence for failing to meet the terms of the plea agreement.