It’s a good test to see how censorship resistant the internet can be.
If you get 5000 from a twitter mob, from people living all around the world, you can still report, but there's pretty much zero chance that anything will happen to any of those 5000 people, because the threats are considered as "not real" and nobody wants to deal with 5000 cases (paperwork, warrants, judical process after, etc.)
For example in Australia, employers have a duty under workplace health and safety legislation to provide a safe workplace. And similar legislation exists in most countries.
If you have an employee who is receiving death threats, you do nothing about it and then they are killed (or they even just sue you) then you would absolutely be liable.
If you're running a business you have duty of care obligations as a Director.
You seem to be completely ignorant of the seriousness of situations like this.