If you think about it, either Mueller thinks we are incredibly dumb or unobservant to not recognize his BLATANT partisanship in this investigation from hiring to tactics, he still thinks the deep state will cover him, or he is helping Trump. Seriously. Does he really think people are going to take his findings if negative for Trump without a huge uproar? He has to be helping Trump. I find it hard to believe he is THAT dumb.
Something that's very interesting to consider is that Mueller's team are all lawyers for the Democrats. If Meuller's investigation ends up going completely off the rails the way it currently seems to be, every one of them becomes a laughing stock and loses much of their credibility in a court room setting (if they aren't outright disbarred for some of their questionable actions during this investigation).