But busing is different. It will affect large numbers of people directly.
Just think about that Detriot busing order. All those suburban parents who are going to have to see their children spend an extra three hours a day on a bus, to go to a less well funded, more dangerous school. (And for that matter inner city parents also aren't happy about having their kids have to spend all those extra hours on a bus.) All of those parents are going to be very angry. And that anger is going to be reborn every single school day. The busing issue has a power that most social issues don't have because its a direct attack on people's children. There's a reason that 85% of the people were opposed to busing.
Another thought: with two successive Democratic administration carrying out the 1964 Civil Rights Act, the Warren Court doesn't *need* to be as activist as in OTL.