I'm of the opinion, just state your case, make your examples, etc.
For instance I'd have brought up the various religious people who think they're right and have no regard for the free speech of other religious opinions. That they believe that those opinions are not only wrong, but dangerous and harmful to society.
Would you want any one of them deciding who gets a platform?
I got what you were putting down. But then again, I'm already of that opinion: That what can be used against my enemies can be used against me, so you better be damn careful about what tactics you allow.
But not everyone subscribes to that thought and people who are convinced that "there are no bad tactics, just bad targets" are hard to convince. They're already convinced of their moral righteousness, that they know the bad targets and that they'll never be the target because they aren't "bad".
And becoming a target doesn't necessarily change their mind either. For some people, that's enough. They realize that some tactics are bad. That the act of choosing to use them is bad. That not all tactics are applicable to all situations. That there is something called an inappropriate response. But others, they'll just figure that people who see them as bad are bad themselves. Their worldview doesn't really change. They cannot conceive a world in which their worldview doesn't eventually have power to right the wrongs because they are right.
The simple fact that some good people just won't like you doesn't cross their minds. That being right doesn't confer upon you any advantage in any sort of struggle is an absurd concept to them. That they may not even be right or that the situation may be more complicated than a simple right or wrong doesn't play to them.
In that case, I don't know what you do.