I doubt it. "Strong enough to fight this Lord Sidious, you are not." Palpatine killed three Jedi Masters in seconds, all Council members and Obi-Wan's peers. While the duo might give him a hard time, it would end the same way, except Obi-Wan would probably die and Yoda would scurry away, leaving an fully human Darth Vader to run amok. I don't deny Obi-Wan is powerful, he defeated Darth Vader, Darth Maul and General Grievous. But in ROTS he's easily defeated by Count Dooku's Force abilities, and we've seen Sidious display the most powerful Force powers in the Saga. Obi-Wan would put up a better fight than Mace's posse, but in the end he wouldn't be able to beat Palpatine. Yoda probably thought the same or he would have brought Obi-Wan with him to fight Palpatine. After all, he was clearly the greater threat, without Palpatine, the Empire crumbles.