I did wonder about that, certainly. However this one seems to lack some of the characteristics of Theorist. There isn't the same level of nonsense algebra, nor the obsession with clocks, nor the telltale habit of lobbing in new bits of nonsense periodically, to keep the pot boiling. In fact this one seems utterly obsessed with saying the same - nonsensical - thing over and over again. So if it is he, then he has changed his methodology quite a bit - different drugs, perhaps?
On the other hand, post 12 does sound like Theorist...