There isn't an upside. They're just as stuck as the Democrats are. Mitch isn't dead, he's likely severely incapacitated. They'd love to have him on the Senate floor voting R but he isn't healthy enough to do so, and the only way to remove a Senator is expulsion by a two-thirds vote in the Senate. That certainly wouldn't get enough votes and, at this point, is pretty irrelevant anyway since the seat would simply remain vacant.
But you are correct that as long as he's ill he isn't voting, which is a good thing, which is why there was really no need for people to be all over Andy Beshear's nuts this past month.