Mu's zoning is also very risky, she has just as many on-demand tools as Rachel, one. And even then, 236a has slow startup and easily loses to correct play by the opponent, on top of that, it's almost useless in a variety of matchups (Hakumen especially). I would say the character advantage of Mu is the might higher damage output, but let's be honest, she does more damage than any character in the entire game.
I personally think the lamest thing Mu has in this matchup is level 2+ SoD, because it's near impossible for Rachel to punish on both startup or recovery, and she only has 4 primers.