Remember that Mr.4 also broke Usopp's skull and was then defeated.
All that this chapter provided was an accumulation and more tension for Usopp and Nami vs Ulti and Pageone.
Nami is without Zeus and Ulti needed P1's help to get out of the Usopp trap, all Usopp and Nami need is to wake up haki and use their power-ups