Deplatforming from what I understand works in deradicalization at the population level. That is, if you want a smaller population of radicals, you deplatform them. If you want less radical behavior, you deplatform them.

(NOTE: the following paper also covers what happens to the radicals who remain radicals post-deplatforming, which is super interesting.) https://journals.sagepub.com/doi/full/10.1177/02673231209220...