I obviously know that now, but it isn't exactly obvious if you haven't stayed in one of these properties before. Since this policy seems to be a departure from the SPG norm, is it really asking too much to signpost this in advance of a stay either upon booking or in the pre-check in email?

The other shortcoming is that since there were clearly unsold suites one way to have resolved the lack of Plat upgrades would have been to offer a decent rate on a paid upgrade. There is no conflict there with Plat upgrades (since no-one gets one anyway) and it allows the property to sell an otherwise unsold suite.