Get over it man.
It happens... especially that the TIMING of his crew being arrested, and outta nowhere, the enemy started to know the crescent moon thingy.
As she stated, they have waited for 20 freaking years for the right time to overthrow Orochi. When you wait for 20 freaking years, and get the most painful 20 years of your life, cause unlike Kinemon and co who traveled through time, and didn't suffer a single thing.
She is much like Asura Douji, who were present and suffered in those 20 years. And we saw how Asura Douji have doubts about the alliance telling Kinemon that they have been abandoned when there was no body there. While Kinemon and some others have much more trust. Asura is telling him to stop.
Point is, the likes of Asura and Shinobu is much more logical to see them skeptical about the alliance. They don't even know Law or of he's good person or not. Why wouldn't they assume that if his crew got caught, and immediately after that, Hawkins and Drake coming in talking about crecent moon. We as viewers surely know Law and his crew wouldn't do that because we know they are good loyal people. But for the likes of Shinobu, they DON'T
So, try to put yourself in their shoe, they have seen the suffering for 20 years.