I'd like to now add one thing to this thread, and that is that the new hotel ownership has now contacted me to re-confirm that my points won't be honored and with this note:

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Please contact us at your earliest convenience to have applied the best available rate we can offer on the same dates.... Should we not hear from you back, we will consider your reservation as reconfirmed to the best available rate.
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Now, consider that I emailed last Friday to ask what the rate would be and so I have now asked the same of the new people (no reply yet). But a classy hotel would have stated the price of the nights in the email and asked me if I'd like to keep them - not simply tell me that if they don't hear from me they'll consider me confirmed at a mysterious rate of their choosing. I also presume (but don't know) that they would be holding it guaranteed to the credit card the points reservation was booked under. Nothing to do with SPG here - just with new hotel ownership.

Still would like to know who owns the place now....