i think when she first met kaido, big mom said Rocks was a terrible person and we know what a morally upstanding woman she is so if even she feels that way….
He felt betrayed when they shut down his favorite McDs joint and went straight ahead to MacTonight Figarland's island to do a little trolling(Karens call it "terrorism"). Little did he know MacTonight's son, the Red Rat AKA Shanks was born a few weeks earlier and he possesses the most powerful CoC since birth, so using his Color of Confidential-informant they were ready to counter.