In Japanese variants, he is correct. When Sony westernized the playstation controller, the O and X functionality was flipped.
Sony is yet to comment on the reasons why.
It might be because of Sega's consoles, which were more popular in the US than they were in Japan, where Nintendo ruled.
The Genesis' button layout was A,B,C arranged in a diagonal from bottom-left to top-right. A was usually 'accept'. The Dreamcast had a diamond with A at the bottom and B to the right.
Nintendo's Famicom buttons read A,B from right-to-left, and that trend continued with the Super Famicom's diamond, which had A to the right and B at te bottom. The N64 had a weird layout, but again B was to the left of A.
Sony probably focus tested the pad in the US and found that players were more used to Sega's layout.
As I said in another comment, almost every Megadrive game I've played lets you use both A and C for accept in menus, so you could use whichever orientation you were more comfortable with. I think anyone who started with Nintendo consoles would instinctually rest their thumb between B and C.
My guess is that Sony thought that X and O wouldn't have as obvious connotations outside of Japan, and figured that people would assume the button closest to the player (X) would be the OK button. In practice, I have found that people with very little exposure to Japanese culture still have the same association with X and O in their heads and get confused when using Playstations ("you press X to accept???"), so I'll curse Sony forever for this stupid regional change.
This is almost certainly a result of intense focus testing, so I don't think it would be a design choice by Sony based on cultural differences so much as an observation of user comfort and expectations.
That's not to say that those expectations weren't due to cultural differences.
I always thought the reason for the switch was down to driving games, where X is a more natural fit for 'accelerate'. Also, X to me is a more 'definitive action' symbol compared to O, make of that what you will.
AFAIK it came close, but the SNES launched later in the US and the Genesis sold more units. As opposed to Japan where the Genesis didn't really get a foothold.
I thought the popular rumor was this was to help people with Nintendo 64 muscle memory, where the X corresponded (loosely) with where the A button was positioned, and the O corresponded to where the B was positioned.
IMO one of the most short-sighted decision made Sony Entertainment EU/US. They had a standard and decided to change it just for the sake of changing it.
The Genesis' button layout was A,B,C arranged in a diagonal from bottom-left to top-right. A was usually 'accept'. The Dreamcast had a diamond with A at the bottom and B to the right.
Nintendo's Famicom buttons read A,B from right-to-left, and that trend continued with the Super Famicom's diamond, which had A to the right and B at te bottom. The N64 had a weird layout, but again B was to the left of A.
Sony probably focus tested the pad in the US and found that players were more used to Sega's layout.