My reaction would be to dislike the performer for lecturing me. Unless I agreed with the views expressed. If I felt strongly enough I would say something to organiser or performer.

If the ladies did not hear the whole concert and presumed the performers were not ballanced in the second half - then they would have to prove that, and accept they did not assess it fully. And if they interrupted the flow of the concert in any way you may have a counter-claim.

But I ain't no expert on legal matters and certainly not in another country.

Are the regulars to your concerts any help in providing suggestions or letters of support?

I did it once for Maglan (Princess Dinizulu) when a landlord tried all measure of tricks (on me as well) and she had to go to a small claims court when he instigated proceedings. I (and many of us) wrote to the judge. She won. She was collecting for charity.