ross has always said he wanted a Simultaneous worldwide release, so probably something out of there control.
Yeah: I think simultaneous release was always the plan. given Ross's constant hints that it WOULD be here on the 4th.
Although he confirmed that "ensuring that no-one in the UK could get information on release date, availability or pricing was a "strategy"" and that "when you know the facts it was a perfectly reasonable move that worked" that *doesn't* indicate that they intended a delayed release: just that the strategy was to keep it unknown in that press release.
Given that IF it comes out on the 11th, it is up against what may well be the biggest 360 release in this half of the year, I can't imagine that it was planned originally, but given the retailers all changing their dates now, it looks increasingly likely at this stage.