User blog comment:Omega natsu2/Chapter 353: Exorcism, Predictions./@comment-5894890-20130920205503/@comment-7418318-20130921092625

Well... in the Espada fight fleeing would have meant certain (even if delayed) death (either executed for desertion if the Shinigame won or hunted down by the Espada if they didn't), while fighting meant at least a chance for survival.

With the Quincy's proclaimed goal of wiping out the Shinigame, the current fight isn't any different. Fight any maybe die vs. flee and die later for sure. And in addition he'd have to forsake his family.

Picking very likely death over certain death is a choice most people would embrace gladly.... at least those that are still able to think at least somewhat straight rather than panicking completely.