Historically, Codemasters was among the first companies to pull away from Nintendo's restrictions and back Sega. For example, they released their Micro Machines games much earlier for the Megadrive and as slightly superior versions (the second game had a build in multitap in the cartridge).
Even though that's the only reason he directly hints at, I also strongly suspect that:
1) Codemasters has a good deal of financial investment in the PS3/360 platforms in terms of graphica/physics assets and any long term software projects that take years to develop
2) Codemasters have no clue how to appeal to young girls, women, or the elderly
Which would suggest that even if these companies didn't fear monopolistic tendencies like the one you're describing, it would still be an uncomfortable situation for them. Leaving the 360/PS3 quite probably means leaving behind a substantial amount of development funds. And why would they do this? Apparently, to attack a market they don't really understand and have never even attempted to cater to.