I know she needs someone like him, but how would she know that. "Dear Khaleesi, as proof of my undying loyalty to you, I bring you this random dwarf who you never met, but I assure you he is going to help you make much better decisions."

Yeah that should go well lol

(Unless does he think she'll see that Jora could have returned Tyrian to King's Landing and opted not to, and that's proof of his lack of allegiance to them? Does she think a Lanister hostage would be valuable? What kind of proof would she have that he is really who Jora says he is?)