I don't think that he gathered these companies to discuss this particular topic...
I can't say that I understand what his angle is here....
Is he looking to get various entities shutdown, like they are trying to accomplish with the infinity chan? If so, what is the gain in that? Is someone assuming that if we don't allow people to express their evil thoughts and emotions on the Internet, then those evil thoughts and emotions are just going to simply disappear?
Or does he want to follow-on with that part that he talked about in his Monday speech.... about getting cooperation from these companies to "identify" the mass shooters based on their social media posts? That sounds like a real winner.... yet another "algorithm" that will be developed to ensnare people for their thought crimes.... Sounds like that would work out really well for members of his base....