Hard to know where to start. The need for ideological diversity is very real. Though the speakers mentioned are not the ones that should be supplying it. It would be like having that professor that said all heterosexual sex is rape be the spokesperson for the left to right wing groups somewhere. If your goal is just to reinforce the idea that the other side is crazy that is who you trot out.
For some reason in modern society we seem to amplify the voices of the self serving and those with extreme points of view. Rather than people who pretty much all want the same thing, but have different perspectives on how the world works. College campus and the media in general are so biased these days that educated people seem to have a hard time understanding the difference between the two. Everything and everyone is so tribal in regards to how they view things. The end result is bad for most of us and good for those in control. We are all so worried about the other side that we don’t even question our own. That’s a problem.