In September of 1993 both SEGA and Hitachi went public to confirm the Saturn would be using a SH-2 and that Hitachi staff would also be based in SEGA HQ. In fact I think in some of the early Saturn credits you'll see Hitachi staff credited in area's like the programming tooThey'd probably settled on using a SuperH chip by mid 1993
More rummor and going on the fact, that System 32 used the CPUI think that's just rumor mill, or only an early throw-away idea
Well lots were caught out not least SEGA who in early 1993 were doing deals with SONY on games like Ground Zero Texas I doubt that would have happened if SEGA really thought SONY would go it alone . What caught everyone out was the spec's that SONY were quotingThe entire mythos about the PS1 and Sony's grand entry into the video game industry is wrapped up in "catching Sega with their pants down".
1,5000,000 polygons/sec plain
500,000 polygons/sec textured
Typical SONY bullshit hype , but it worked and for sure SEGA (added a 2nd CPU) and NCL had to rethink some of their plains (there was even rumors of an split between SGI and NCL) . That's what got a people of people off-guard was the spec's of the machine, more than the fact SONY made its own console