After threatening to close my account unless the fee was waived, I received the following offer to "convert" my card to the regular MP credit card:
Newly established accounts with a 1K premier status can
only have a $60.00 maximum annual fee waived on their
credit card account. If you would like to convert your
Platinum $140.00 annual fee card to the classic Mileage
Plus $60.00 Signature card, where you would qualify for a
full annual fee waiver, please let us know. If you would
still like to close your account, please respond through
the same secured email.
Still no luck getting the full $140 waived.