I don’t see how her choice to decline the invitation would affect her career. Not going seems like a non-issue that will barely even enter public discourse.
If she had gone and protested, she might have been dropped by her label (I don’t know how progressive Island Records is). Even then, the “no such thing as bad press” axiom might have worked in her favor. It seems like her fan base is pretty fervent, meaning she would likely be attractive to another label.