is one piece episode 304 filler?

We recap to the point the Buster Call shoots the Tower of Justice. It's revealed that Sogeking fell from the struck section and into the base of the tower where Sanji and Zoro were located, avoiding falling with the rest of the section into the abyss.

Meanwhile, on the Bridge of Hesitation, Franky and Nico Robin (just freed from her cuffs) prepare to fight their way past Spandam and the Marines to reach a getaway ship. At the same instant, Luffy is still fighting Rob Lucci in the first column.