> At the same time, I'm surprised they can't get this classifier to work. It doesn't seem like a very challenging problem
Why are you assuming that they can't get the classifier to work? There's no evidence to that effect in the article.
> I wonder if they're over-reacting and just deciding to zero any residual risk by not allowing that classification anymore.
Why do you describe that as over-reacting? It seems like the appropriate level of reaction given there is no upside for getting it right and a massive downside for getting it wrong.
It doesn't even need to be a top-down edict, it's just the way the incentives will work out for everyone involved.
Let's say that you're an engineer working on that team, and find that there's a bunch of terms added to a blocklist a decade ago and still there. Are you going to just remove them, on the assumption that the classifications are correct? Of course not. How much validation work are you willing to do to convince yourself and others that the results are 100% correct? Is that really going to be the most interesting or impactful work you can do this quarter?
Similarly you'd find that whoever needs to approve such a removal would have incentives very strongly biased toward not approving the removal of terms from a blocklist. If everything goes well, they get no credit. If something goes wrong, they get the blame. It's possible to push through that bias toward inaction, but it requires it to be a change that somebody really wants to make happen.