That certainly was amazing.
I was going to harp on about how letting Eri get hit by her own quirk isn't actually all that bad since:
1) it'll end the crisis of having humans rendered quirkless, and
2) will that actually do anything anyway? Eri just got a dose of Eri.
Anyway, I guess there's no guarantee that thingo was gonna shoot anti-quirk bullets (despite how good at predicting Lemillion is), so he did the Hero thing.