Brown never "killed" Pluto, and his obsession with the idea that he did is completely unprofessional and unscientific. It is nothing more than a means of branding himself to sell books and gain money and fame. Kirby Runyon's planet definition makes a lot more sense than that of the IAU because it is focused on an object's intrinsic properties rather than on its location. There is no need for kids to worry about memorizing 100 planets because memorization is not important for learning. It is an archaic means of teaching from a time when we knew little more about the planets other than their names. Instead, kids and adults should be taught the different subclasses of planets and their definiting characteristics. We don't ask kids to memorize all the elements of the Periodic Table or all the rivers and mountains on Earth, and similarly, we don't have to ask them to memorize a list of planet names.
Brown is out and out wrong when he says that worlds like Pluto have more in common with tiny, shapeless asteroids, comets, and KBOs than with the larger planets. Pluto and the other dwarf planets have all the features the larger planets do. They have geology and weather and are layered into core, mantle, and crust. The only difference is the dwarf planets are smaller. The Dawn and New Horizons mission clearly revealed many active planetary processes on Ceres and Pluto, both of which may have subsurface oceans that could host microbial life.
Brown is also wrong in saying that just a small but vocal group rejects the IAU defintion and has been advocating for a geophysical one. This is blatantly untrue. While some people are more vocal than others, there is a huge cohort of planetary scientists, amateur astronomers, educators, writers, and informed members of the public who never stopped considering Pluto a planet and oppose the IAU claim that dwarf planets are not planets at all. We have actively promoted a better definition including dwarf planets as planets for over 10 years and will continue to do so.