I think you are taking what he is saying out of context and being very dishonest about it. He is not talking about diversity meaning he doesn't want different races or sexualities involved in the country. He is talking about the extreme fracturing of groups that is driven by social media.
I see this in my everyday life. Browsing any forum, almost every view expressed by any person is polarized to some side. However, being older and having enough people not connected to social media in my circle, I notice no one expresses the same polarization of thought that is so prevalent in social media and online communities. I also notice that the few people I interact with who do spend a large amount of time on social media are extremely polarized and mostly miserable.