One thing I found fascinating is that, with a sizable majority (I set red to around 80%), the minority actually becomes less stable if you set a moderately low

One thing I found fascinating is that, with a sizable majority (I set red to around 80%), the minority actually becomes less stable if you set a moderately low threshold for moving. With a high threshold (like t=67%) you get very rapid clumping as both reds and blues try to move into areas where they're in the majority. But with a low threshold (like t=25%) the few majority people who are isolated move, minorities quickly fill the open spots, and then the only remaining locations for minorities are completely surrounded by the majority (while no more majority members ever move). So the minorities just shuffle around between a bunch of unacceptable locations, none of which give them the 2 minority neighbors they require. Then there's a sudden transition when t gets low enough, at around 16% -- the minority will tolerate having only one similar neighbor as long as there's also an empty spot, and therefore they stabilize very quickly. So when the threshold is high, there's a lot of churn early but then stabilization. When the threshold is low, the tolerant majority stops churning quickly and therefore stops opening up spots the minority finds desirable.