The reason why he once again threatened people with litigation is because it has worked successfully several times before. As soon as someone said anything negative against him, he would push the litigation red button. He has successfully closed channels down and scared people away by threatening to sue them.
The problem this time though is he went after people that he has already threatened litigation with in the past. You have to be incredibly stupid to actually think that unsuccessful attempts to intimidate the same people time and again will have the same desired effect.
He's created a paradox that he will never recover from, no one will ever believe or take his tantrums seriously again and I believe that is why we don't hear much from him now.
Once you stand up to a bully they cower away with their tales between their legs. There are too many people who will not stand for his tantrums anymore and he must be acutely aware of this.