That’s because he’s a crappy jurist.5-4 to overturn Roe and Casey
6-3 to uphold the Mississippi Ban
Roberts is the difference, as he doesn't like Roe or Casey, but he doesn't like to overturn prior decisions either, so he would have just weakened Roe and Casey again and waited for another case. He liked to whittle away at the underpinnings rather than blow them up.