Sorry, but this article is total bullshit. Here's why: They list four possible responses to your child being bullied, including standing up to the bully, ignoring and avoiding the bully, involving the parents of the bully, or involving the teacher/school. They state that these are all likely to be ineffective. That said, their problem with kids standing up to bullies isn't that it's ineffective, though they paint it…
Whatever else you may have to say about how this is "total bullshit", this article isn't the standard half-educated reporter writing whatever comes in their head for The Guardian. Alan Kazdin has more scholar hits in his field than anyone commenting here has for theirs. You're right that there's not a lot of data in the article that backs up his point, but you'll be wrong if you follow that logic to the conclusion yo…
1. None of that data is presented.
2. He leverages mockery to preemptively discredit people with real-world experience that disagrees with his position, despite offering no evidence, experience, or data of his own. Come on, linking to a standard response that someone who disagrees with him can use to come up with their own formulaic response? Clear anti-intellectual mockery, and hardly the mark of a rigorous scholar.
3. His logical process as presented in this article makes absolutely no sense, particularly with regard to why telling your kid to stand up for themselves is a bad idea.
To repeat an analogy I used in another comment: this is like saying that you shouldn't advise someone whose website just got hacked to secure their app, because they got hacked because they didn't follow proper security protocol, and are therefore unlikely to follow your advice.
To accept the article as a well-written and well-argued piece on the proper response to bullying, just because the author is a leading scholar in his field is just a bizarre kind of reverse ad hominem.
Edit: reworded a few things