Roughly translates to:
"Salute to the commander and leaders of the revolutionary army. Be a revolutionary, or die trying."
Salute in arabic culture usually refers to the dead, not the living.
-- In hindsight, this does make sense since Oda did say that Fujitora and Greenbull were fighting the revolutionary army at reverie. Greenbull showing up at Wano after dealing with an invasion of reverie means they beat the revolutionaries there. I doubt they'd let the revolutionaries get away after invading reverie.