I would point out that Mill himself puts in a big loophole in his defense of all expression. Specifically, he says that
the only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others.
This is typically known as the "harm principle." An example of this, he said, would be that you could prevent someone from telling an angry mob of poor people outside a grain dealer's house that the dealer is starving them.
Given this exception, I would argue that it is correct to advocate complete freedom of expression. I would argue that it is necessary to think of this exception very narrowly as well. I think that if you define "harm" too broadly, you could really devastate free speech.
But I can think of no kind of speech that should be suppressed if it is not going to harm people.