If you are a whistleblower, and you claim something is illegal then I don't expect you to accurately make a case that it is so. You may have just felt it was illegal, when it was not and I'll give certain leeway in making the wrong decision there.

However if you are a lawyer, and not only that but the supreme prosecutor of the Federal government, you ought to be able to properly define why something is illegal not just publish a press release that essentially says "it's my gut-feeling this will fail".

She is supposed to make the best case possible for the presidency and allow judges to decide if something is illegal, and someone is guilty or not guilty. Simply saying "he's guilty, I'm sure, but no I can't tell you why" is not a solid answer.