Is it wrong to be against a rational discussion of the benefits of race-based slavery?
Is it wrong to be against a rational discussion of the benefits of child-slavery?
Is it wrong to be against a rational discussion of the benefits of childhood labor?
Is it wrong to be against a rational discussion of the benefits of racial discrimination?
Is it wrong to be against a rational discussion of the benefits of gender discrimination?
For some things, allowing that rational discussion is a reasonable option legitimizes things that should not be legitimized because they are against the very nature of human rights. For example a rational discussion of race-based slavery is something that legitimizes it as something within the bounds of reasonableness.
I don't know where the boundary is, but I'm sure that is isn't obvious that anyone arguing against having a rational discussion.