While the bravery of those who stood and fought against hopeless odds for their lords are celebrated, the ones who turned tails and fled are not considered dishonorable in any way. They were, after all, just trying to live another day. Living and winning are the goals of the samurai, nothing was considered dishonorable to do so.

We have plenty of tales of samurai running away from disadvantageous fights (a couple of which is cited here) that's not treated as anything except a practical, matter-of-fact thing to do (the old guy was even boasting of his skill of running away from an outmatched fight). There are case after case of armies retreating from a disadvantageous position without fighting at all. There's even tales of, for instance, a samurai and his band losing a fight, running away, hiding in the bushes, then regrouping and coming back when their adversaries are drunk and asleep to burn the building down and kill everyone inside.

In fact, it was considered stupid and rash to join a fight when you don't have to or is disadvantageous (unless, say, you're a foot soldier loyally buying time for your lord's escape). In the Taiheiki, Nitta Yoshisada challenged Ashikaga Takauji to a duel, and Takauji wanted to accept, but were stopped from it by his followers for being too risky and unnecessary (Takauji's army was winning). Similarly, the sources do not praise Takeda Katsuyori for deciding to fight a pitched battle against an army over twice the size of his own. They criticized him, saying he should have retreated or holed up in a castle or on a mountain.