You seem to assume that MWI makes the Sequences more vulnerable; i.e. that there are people who feel okay with the rest of the Sequences, but MWI makes them dismiss it as pseudoscience.

I think there are other things that rub people the wrong way (that EY in general talks about some topics more than appropriate for his status, whether it's about science, philosophy, politics, or religion) and MWI is merely the most convenient point of attack (at least among those people who don't care about religion). Without MWI, something else would be "the most controversial topic which EY should not have added because it antagonizes people for no good reason", and people would speculate about the dark reasons that made EY write about that.

For context, I will quote the part that Yvain quoted from the Sequences:

Everyone should be aware that, even though I’m not going to discuss the issue at first, there is a sizable community of scientists who dispute the realist perspective on QM. Myself, I don’t think it’s worth figuring both ways; I’m a pure realist, for reasons that will become apparent. But if you read my introduction, you are getting my view. It is not only my view. It is probably the majority view among theoretical physicists, if that counts for anything (though I will argue the matter separately from opinion polls). Still, it is not the only view that exists in the modern physics community. I do not feel obliged to present the other views right away, but I feel obliged to warn my readers that there are other views, which I will not be presenting during the initial stages of the introduction.

Everyone please make your own opinion about whether this is how cult leaders usually speak (because that seems to be the undertone of some comments in this thread).