IMO it all comes down to the fact that the game will likely sell good on the 360 regardless and (more importantly) CoD has made more of a name on the 360 so it makes sense to tie BF3 closely to the PS3 in this case. Nothing wrong with this move and it makes perfect business sense to try and make a bigger impact on the PS3.
The market for FPS aren't simply going to grow out of nowhere for ps3. It's as big as its going to be. In fact it's still quite big with the ps3 version of Cod selling around 8-10 million units worldwide ( according to vgchartz ) on the last entry.
Those people who you are talking about that own a 360 for Cod simply aren't going to switch to Ps3 because of EA's marketing gimmicks. Unless the game is totally broken on the 360 ( which would be bad business if they like money ), I doubt you are going to see any impact whatsoever on the Ps3 version of the game.