is one piece episode 520 filler?

Brook finishes his concert and thanking his fans. Later, he goes backstage and is given a bottle of water and pours the water on himself.

Later on, his fans call for an encore which he accepts. The Marines then come and want to arrest him because he is a member of the Straw Hats.

Brook starts to sing his last song, proclaiming that Luffy is still alive. The Marines open fire, but Brook already escaped on a flying fish.

Chopper, Usopp, Robin, and Nami later reunite at the Thousand Sunny. Chopper and Usopp meet Franky again and seem to be amazed over the new equipment of his body.