They can claim discrimination and many other such claims. It seems there's a lot of evidence to support criminal negligence. If inaction led to deaths a civil suit can get a big payout.
Otherwise it would be a precedent for creating algorithms that break the law.
BTW, you are 100% reasonable I do not understand the down votes.
I believe it could be true because it doesn't seem that different from reports[1] a few years ago talking about how YouTube would push more and more extreme suggestions.
IIRC YouTube made changes pushing people towards more mainstream content and away from small producers in part to avoid extremism.
[1] https://www.theverge.com/interface/2019/4/3/18293293/youtube...
It is designed to reinforce existing beliefs and preferences in order to increase engagement.
In this case the beliefs were virulently racists and bigoted, and the engagement was usually done with a machete.
And it turns out that hate, fear, and tribalism are great for that.