Yoda's penance image - SW cantina

So instead of trying to fix things by teaming up with the Rebellion, Yoda just went into self imposed exile after just a single failed attempt to end Sidious. He didn't even let the rebels know that they're up against a Sith Lord considering Palpatine's true identity was unknown during the various rebel assassination attempts on the emperor.

In short, Yoda's choice to exile himself was rather pathetic when he could have spent that time gathering/organizing the remaining Jedi and creating a rebel alliance to face off against the empire. Sure he needed to be around for Luke or Leia to get trained but he could have done that while helping the rebellion. Although the empire would have been absolutely ruthless in hunting him and his allies down should he reveal himself but it'd probably have been better for their survival if they stood as a united force against the Sith instead of letting themselves get individually hunted down. It's far harder to kill a dozen Jedi at the center of an army than a single Jedi that got found on some remote world. The later can be taken down by an inquisitor or assassin while the former at least requires an equivalent army. Even if the plan was to outlive the Sith it was overly optimistic and didn't take into account that Sidious knew about essence transfer which made the whole plan pointless. I guess the Sith could have more easily sensed the Jedi if they had all gathered together to command the rebellion from the start and the empire always had the upper hand over the rebel alliance in basically every regard but still, having powerful Jedi like Yoda backing them early on could have helped the rebels rally faster.

Of course an all out war with Sidious could also just result in a repeat of the New Sith War in which the Jedi and Sith nearly destroyed galactic civilization given that conflict effectively destroyed the Republic requiring it to be reformed in the Ruusan Reformations and technologically regressed the entire galaxy given the tech that that's found in the Rise of the Empire era is worse than some of the tech developed and found during the Great Galactic War of the Old Republic. So maybe going into hiding was better than dragging the galaxy into another squabble over religion.