Even he admits there are two engines. And then he jumps to VSTOL. I know of no fighters in history that have more than one engine and are capable of VTOL. And does anyone really think the PLA currently remotely want anything as complex as a VSTOL stealth (or even non stealth) fighter in the first place? Honestly if I was him and saw the twin engines and the seemingly stealthy shape and discucsions on blogs and forums I'd immediately compare it to the other legions of twin engine F-35 class paper planes currently being studied by the japanese, koreans, indians, turks and what not. Makes me wonder if there's a failure of logic when he wrote it or is purposefully trying to be obtuse.
And again another western observer chooses to link J-20 with Mig-31. Le sigh.