I just have a strong feeling that Kenobi wipes Leia’s memory because she finds out something. Maybe she learns her father is the man in that horrible black mask. It might be too traumatic for her, so he removes those memories of them together and her learning the truth.
Remember in Return of the Jedi, when Leia says to Luke, “I know, somehow I’ve always known.” She knew Luke was her brother and Vader was her father, but Kenobi removes it from her memory. When Luke reveals to her they are brother and sister, some of those memories return to her.
I also think he tells young Leia that if she ever needs him again, she can find him in the Jundland Wastes on Tatooine. Maybe R2-D2 is there when he says it, that way he knows exactly where to go on that big planet.
You found theories to make the show even worse…