There's 2 different parties under discussion here, the other streamers and the platform.

Regarding the streamers, I agree there might be room for a manslaughter charge. IANAL, much less in French law. Personally though, I don't see how it differs substantially from any other high risk group activity. If you're free-climbing (or maybe some other activity that involves more chance and less skill), and you're doing it voluntarily, knowing the risks, is it really fair to blame the survivors if somebody dies?

Regarding the platform, up until the point where a death actually occurred, what could they have reasonably done that would not have constituted some form of censorship? At that point, aren't we back to the censorship discussion of how much power platforms should have over the content we have access to?