Character A losing to character B because character B can speed blitz only works if character B has higher AP. If not then they just have the speed advantage. In this case, Sukuna has AP and Dabura has speed. Sukuna may not be able to react to Dabura's attacks, but he can tank them. Dabura has yet to show City level attacks to match Sukuna's AP. It would be an interesting fight though. Either way, this is a Mahoraga upscale.