But his actions *do* show that he will take Anakin back. He talks to Anakin for about 10 minutes before understanding the fact that Anakin isn't going to back down. He tries once again near the end of the fight to talk to him, but that fails. You also see the desperation in his voice and face when he realizes Yoda wants him to kill Anakin. He doesn't want to do it even though he saw with his own eyes Anakin fighting the Younglings. He even makes a last pathetic attempt to not fight his friend. He tells Yoda he doesn't know where to look. Obi-Wan, like Padme, is grasping for any last hope that Anakin will turn back.