That is by far the best response. Don't say why you chose to shun such people, just avoid talking to them when it is avoidable and keep any essential conversations as brief as possible even if a longer conversation would be more productive. Anyone who files a frivolous complaint or lawsuit needs to be shunned by everyone decent.
“Anyone who files a frivolous complaint or lawsuit needs to be shunned by everyone decent. “
I knew a woman once who filed a frivolous sexual harassment suit and accepted a token settlement from the company.
After that no one in town would hire her and she had to move out of state for a job.