I followed the saga, or rather the bits of it Maciej mentioned here and there, and I bet the price was not high. Basically the owner was bleeding money with shocking AWS charges, and was looking for a way out himself. I expect one of the reasons that it's going read-only so quickly is to turn off the saving/replicating machinery and cut bills. Once he does that, he can probably turn on export features again.
I wonder what is so wrong in delicious' backend that is so expensive to run. Maybe that's why Yahoo ditched it, for some reason it's a money pit...? Note how Maciej is explicitly saying he will never turn it back on, not even redirecting the api endpoints which should be trivial. There must be a reason for that.