It's funny that you think Mueller didn't express an opinion. He violated the rules of professional conduct to get out there with his 'no exoneration' and 'we would have cleared him if we could' formulations. His charge was to indict, not to impugn. Yet, he did the exact same thing that Comey did with Clinton, listed out all of the faults (and some that are only imagined) of the "accused" in a manner designed to cause doubt and impugn his character, in a format and way that brooks no argument.
He didn't have to prove, for example that Trump fired Comey for a corrupt purpose, he just asserted it could have been one and listed it out as one of his grounds. If he'd had to prove it, he would have lost badly, as there are plenty of real time statements that list out Trump's actual basis for firing him.
It doesn't matter. Pelosi has always intended to bring impeachment charges, and to impeach on largely a party line vote. Her intent though, was to time it to maximize electoral impact, effectively to try and eliminate any response by the Senate to clear him, or to bring it so close in timing to the election to try and make the House's investigation the sordid story and not the Senate clearing him, which they'll paint as purely partisan.
All this does, to me, is act to force her to act too soon.
There's no real investigation required. The banana court vote is already counted, but that won't stop the investigation from dragging for as long as possible to ensure that the House Dems and not the Senate holds the narrative.
There's no part of justice involved here at all. The House, the Senate and the DOJ all cleared him of conspiracy/collusion. The DOJ didn't establish facts sufficient for obstruction, and that's using a legal standard that was made up and far beyond what should be applied. And it doesn't matter to the left that they have to burn the Constitution and all our legal protections to get their man, it doesn't matter than no crime was committed by Trump, or that the prosecutors violated the Constitution to build their "trumped" up case, so long as it gets the result they want.
In one way they were correct, Trump's election may be the end of our Democracy, only it's not be because of Trump it's because of the left.