It certainly isn't. What I wasn't sure of is if he had anything new to say about it. There was nothing in the article to suggest that he did.
The unfalsifiability problem is common to discussions of the interpretations of quantum mechanics because they generally are just that, interpretations, so they don't make any predictions that go beyond the standard theory. As far as I know, the only person who is trying to make predictions and do experiments in this area is Penrose who proposes that wave function 'collapse' is a real physical phenomenon that is related to gravity. His view really is a small minority one, though.
This is surely part of Carroll's problem. In the absence of any experimental approach to it, all we are getting is his feels. The book, from the interview, reads as if its going to be The Secret Many Worlds Diary of Sean Carroll, Aged 54 and a Third. I am sure there will be good bits in it as he's an excellent communicator but it feels as if it's a book for the sake of publishing rather than one that has substance.
In the larger sense, unfalsifiability presents a challenge for any area of science in which it appears since as you note what you end up with is discussion of interpretations rather than anyone 'doing science'.
