Update:

> it's now actually announced to be another CPU called S1
> by a chip design company called Solid Silicon

At the OCP Regional Summit two weeks ago, after misrepresenting the launch purpose of the OpenPOWER Foundation (hint: it's still in the letter case) and starting from 1:50, its president (as well as IBM Power Systems director) Meow Yee claimed that Raptor was "developing a generation of Power processors using the Power ISA 3.1. […] Raptor is utilizing that to build a processor for their business".
I guess that actually refers to Solid Silicon's S1 that Raptor wants to use.
The shown slide more correctly reads "Raptor designing ISA 3.1 POWER processor MHS HPM module" (emphasis mine).