While it's not known why Sega pushed the game back, we can consider that it may be something big because it is being slated with a nine month delay. The same length of time it takes to create a human being. While delaying games from Q4 09 to Q1 10 is nothing new, it begs to ask the question, "Why are all these game getting pushed back?" Were the developers just not able to meet the holiday '09 deadline? Were the games honestly not that good? Did the publishers put a deadline that clearly would not be met?
Although the more startling question is going to be, how many of the Q1 10 games will be pushed back to Q4 so that they “have more time to refine and polish the game” and more importantly to the publisher, get the extra boost of sales that comes from releasing a game during the holiday season. While it's true that a game released in March will still be available during the holidays, parents are more willing to spend money during the holiday season to buy video games for their kids, as opposed to a game released in March, a kid might save his money, buy the game used (which nets $0 for the developer and the publisher), and then maybe even return it.
Games like Modern Warfare 2, Assassin's Creed 2, Forza 3, Brutal Legend, Dragon Age, and Tony Hawk Ride are all scheduled to make appearances this holiday season, with Dark Void, MAG, Army of 2 The 40th Day, and Darksiders all scheduled to come out early-mid January, however there is still plenty of time for those games to get pushed back as well.
Alpha Protocol will be released (at some point) for the XBOX 360, PC, and PS3