But this case is black and white, so cheerleading is appropriate.
How about instead of blanket statements we look at individual cases and cheer or scold based on merit?
This is all free speech. Some speech is bad (violent and obscene comments to a teenage girl) and some is good (her dad publicly shaming the perpetrators). Don't get all hand-wringy about dad's good speech, just because "oooo things could also be bad." This is the same inability to make obvious value judgments that gets us TSA agents taking away little old ladies' nail clippers because terrorists might do bad things, despite the fact grandma is clearly not a terrorist.