IMHO his statement seems to be plausible. According to Wikipedia development began in 2008. However it was clear even before PS3 was finally released that lot of studios complained about the CellBE/PPC architecture which required from the scratch development of the game engines.
So after release of PS3 in 2005 and be aware that CellBE will not improve largely in price, speed and lower power consumption the devs in 2006 started to estimate the base architecture for the successor. So there was not a lot left to choose other than ARM, MIPS or X86.
Probably they had a close eye to these and evaluated the platform including possible vendors etc. from 2006 to 2008 where they finally decided to switch to X86.