I think MSU needs the positive of a win more, whereas Michigan needs to avoid the negative of a loss more.
If UM wins, there's no narrative. UM has better players, UM won, he's split with Tucker. Carry on. I think both schools are fine with that. I don't think UM "gains" anything from that.
If MSU wins, there is a narrative. Tucker is 2-0, he's already got MSU ahead of Harbaugh, etc... I do think if MSU finishes with losses to UM, OSU, PSU, and goes 9-3, that's still a GREAT season. I predicted 4 or 5 wins, and said I would happily sign up for 6 and a bowl bid. But as far as momentum goes, it's a pretty hollow 9-3. You win one of those 3, then it's 10-2, a possible NY6 bid, and firmly planted yourself as part of that group at the top of the East. You can sell that in recruiting.