I don't think the platforms should be liable, but one line of argument is that the platforms are not neutral to content. They do their own content moderation and remove content which is illegal or objectionable. Thus, if the Oct 7 broadcasts can be deemed illegal in some context, and if the platforms are already picking and choosing what content to moderate, then there could be an argument that they should've moderated those videos as well.

This was my point about wise kings. You can try to encompass every scenario within the bounds of a legal code, but there are too many variations to get every case right by the strict letter of the law. In the past, you'd have kings and judges make these judgment calls. I guess we still do, but within a much more confined legal environment, as well as much more input from the populace through the election of political and judicial leaders.