It's more of a gut feeling.
Feel like she's dug her hole way too deep, and that there surely are some who are trying to capitalize on this.
I've seen flower fake her annoyed/ angry attitude before, I wouldn't put it past her.
There's not really much resistance here, and even if it was, flower's teammates wouldn't go out of their way to pitch in for her.
this is tinfoil but I think Usopp among the sus people tbh, he feels way too much of a diplomat here. I think Usopp is defending Flower because he knows she's town, and in the not so unlikely case flower gets offed, Usopp will look good for trying to defend her.