If I understand the simulation correctly, this suggests that spaces that are dominated by a majority group probably are for the most part happy to increase thei

If I understand the simulation correctly, this suggests that spaces that are dominated by a majority group probably are for the most part happy to increase their membership of minorities, and might be trying actively to do so. A bigger limiting factor may be the minorities themselves, who feel uncomfortable in a majority-dominated space, even one that welcomes them, and won't make the move unless they can bring enough others along at the same time. Pioneers willing to make that move first are very important. The writing sort of hints that it's the majority group who has to change something to attract minorities and reduce segregation ("demanding a bit of diversity in your spaces"), but per the rules of the simulation, that doesn't actually work. The only effective action that really works is for at least some members of the minority group to be comfortable seeking out places where they're surrounded by others who are unlike them. A triangle surrounded by other triangles cannot improve diversity by welcoming a square. They can only do so by themselves venturing out toward a square-dominated space.