No, I don’t: actually we probably agree about that, with that sentence I was just trying to underline the “being understood” requirement for an effective theory. That was meant to introduce my following objection that the order in which you teach or learn two facts is not irrelevant. The human brain has memory, so a Markovian model for the effectiveness of theories is too simple.
I doubt that you will be successful in convincing EY of the non-privileged position of the MWI. Having spent a lot of time, dozens of posts and tons of karma on this issue, I have regretfully concluded that he is completely irrational with regards to instrumentalism in general and QM interpretations in in particular. In his objections he usually builds and demolishes a version of a straw Copenhagen, something that, in his mind, violates locality/causality/relativity.
One would expect that, having realized that he is but a smart dilettante in the subject matter, he would at least allow for the possibility of being wrong, alas it’s not the case.