It's an attack from Enraged Kidd and sneak attack
Expecting some blood or it'll make Kidd look bad
Like how the dude gonna hit Kaido if he can't do much to Apooo with a serious sneak attack?
An attack from an enraged Big Mom towards chopper ....
No k.o chopper or blood...
We see BM later clashing with Kaido evenly.
By plot Apoo simply cannot be defeated of heavily weakened ( Kid will not spare him ..he will kill him).
Apoo is the perfect tool to distract Kid and avoid him reaching Kaido.
( Cuz is simply too early to face Kaido ).
Story >>> PLs