My understanding is that they say "it seems pretty reasonable to think that ABBA is of good quality, given all that", and then "because it is good quality, then it doesn't seem completely implausible that you may end up liking it someday".

But again, you don't have to of course :-). But I agree that it feels more likely that you may end up enjoying quality music you don't like now than bad music you don't like now!