I can easily think of what they're up to. Keep doin it doin it doin it until they get trump.
Consider that Comey, Muellers buddy, has been bad mouthing the Kavanaugh confirmation, so we can assume hat mueller still has allegiance to his friend the dirtbag who was fired for cause. Mueller should be fired too. He's been alternating between picking his nose and sticking his finger up his butt for two years and he has accomplished nothing related to his original appointed duty. All he has done is abuse power, grandstand, and look busy by indicting people that don't matter to the trump administration.
Assuming what some of the pundits say comes to pass, we can look forward to the mueller investigation withering away under eventual public pressure to end the foolishness. At muellers age and infamy, I think he's a prime candidate for a bout of arkancide after he fails. Maybe he realizes this and is keeping the investigation going just so he can stay alive.