Closing the loop: I didn't urgently need the points (I'd already booked the replacement itinerary) so I went to try out the online cancellation request form. However it turns out an online cancellation automatically applies the 7500-point fee rather than the $60 and that is terrible value. (I can easily get over $200 of value with 7500 points judiciously applied to long-haul J.)
So I cancelled by phone. It took a few minutes, I had the points back instantly, and the original taxes/fees are already credited back to my card less than 48 hours later.
