I haven’t played it a lot, but I don’t think it looks particularly bad for Oni. He can afford to play patient, while Gwen loses 10 life every 5 turns. He’ll want to play a lot more like he’s playing against Zane blodge, 7-throw is very good here.
Also, outside of Q, the speed advantage gets less clear. Q and A beat her A and her other face cards, J beats her J, AA beats her J. 3 attack also beats J, which can be relevant. And FA leads to 10ish damage, plus clockwork damage, as you noted, plus a potential pump for J or K.
And this is where the crux of the MU is, I think: Gwen has effectively 70ish HP, and getting hit by 20 damage is almost 1/3rd of that. Oni has a lot of ways to deal 1/3rd to 1/4th of Gwen’s health in a very card efficient way, and he can usually do it by dodging. Given that you can only joker twice, you’re going to have to raw throw more, which Oni can beat with faster throws or with an attack for 10-20 damage.
In that respect it’s like the Setsuki MU, with two big changes. One, Gwen’s dodge follow-up is worse since she doesn’t have a way to full combo off it. Two, Gwen’s Q is an ender for 10 damage max. Good “get off me” button, but you can’t threaten much off it. I’d be okay losing an attack to Q in most circumstances because you can’t blow me up with it. Gwen’s best combo starter is K, which I can beat with Q or A, and her next best combo starter, 2 attack, also loses to AA.
I don’t know if it’s necessarily good for Oni, but it’s not bad, imo.