Unless SE are crazy they wouldn't have paid for any advert that only noted 360 as a platform. Those should have been vendor funded as part of a promotional contract by MS. Unless, noted, SE are crazy - which I doubt.
Otherwise though you're quite correct. In fact, when you think about it, SE got good sales in Japan and backed Sony there where it counted most to the title, almost certainly got the main TV ads in US/UK funded by MS (I don't know about elsewhere) and I'm sure got the sales on PS3 they would have anyway plus the best shot at decent 360 sales to add to their haul.
Not bad - and I have to suspect Sony might have slipped them a little something to keep FFXIII off 360 in Asia, too... so not bad playing both ends against the middle by SE really.
Try to be reasonable... its easier than you think...
