People are ready to move on from A:CM, and ready for a working Alien game. Sega must know that, and they're better off being quick rather than delay to distance themselves from a bad product. When a bad product hits the shelves, companies don't sit with that being the the last thing in the minds of the consumers, they replace it or divert from it. A companies most valuable resource is it's reputation. With reputation you can do just about anything else, raise money, hire more specialized personnel, expand. It's much harder to start with one of the others and then gain reputation, which is often why small businesses fail. You can have an expert, but without money, there's not much you can do with production and advertisement. With money but without reputation, it can be harder to hire more prominent veterans of an industry. So on and so on.
That is what is being shown here on these forums. Nobody trusts them. Sega knows they've got to knock one out of the park and they have to do it quick. News of CA doing an alien game came out quickly after A:CM, which was the right move. Rather than everybody knowing ACM was bad, we are speculating about the outcome of this new game, and that's a much better gamble than letting the bad product hang in our minds without something new to look at.
If Sega screws this one up, then they are in real trouble. Consumers can forgive a mistake, but they typically don't forgive repeats of mistakes.