Quite honestly, there is no real need for a single AP autoland, except in those very rare cases where the second AP is U/S.
Is that an approved procedure? I've flown 732(Cat 2 man land) B733/734/737/738, and for various airlines. I've never been taught. nor heard it discussed as an approved procedure.
The idea that it might be used in a marginal CAT 1 scenario is because I assume there is no nose up trim. Given, there would be no protected area, hence my thought that LVO's were not in use and you'd have sufficient time to decide, the same as you would on a manual landing but more relaxed. However, I can not say from personal experience because I've never been exposed to it. Hence the questions in good faith.