What allies could he possibly gather?
Neko is already responsible for gathering the WBP remnants.
Jinbe doesn’t know the Straw Hat Grand Fleet, and if they showed up, it’d be because of their vivre cards.
He wouldn’t be bringing Germa or the Sun Pirates. If Jinbe fled and the rest were captured, then why flee in the first place if you’re gonna go back on your own to rescue them? If the rest also escaped, where are they, and why would it take them so long to get here compared to the BMP?