That's pretty damning. Facebook execs knew that extremist groups were using their platform and Facebook's own tooling catalyzed their growth, and yet they did nothing about it.
Seems like the relevance of that line really depends on answers to both. I.e., if extremist is super narrow we may be talking about 64 people out of 100. If extremist is overly broad, then maybe all the recommendations were for groups that a majority of the population would not find offensive.
Just saying the line by itself without context doesn't convey as much information as it first appears.