This chapter has some forgetting how the manga works. Kaido surviving magma doesn't take away from Akainu or make him look weak/bad.
Kaido survived 40 death sentences. We know some of those death sentences involved blade/edge weapons that failed to even hurt him. Yet, Zoro and Oden cut and scarred Kaido with an blade/edge weapon. Why is that? It's because of haki.
If that's true then there is no reason to believe just because Kaido survive falling in magma he can't be hurt with magma attacks coated with haki. If the attack is powerful enough it will hurt him.
Kaido survived 40 death sentences. We know some of those death sentences involved blade/edge weapons that failed to even hurt him. Yet, Zoro and Oden cut and scarred Kaido with an blade/edge weapon. Why is that? It's because of haki.
If that's true then there is no reason to believe just because Kaido survive falling in magma he can't be hurt with magma attacks coated with haki. If the attack is powerful enough it will hurt him.