Sony has a conference at a Games Show in Paris, and it's on the same day Halo 5 releases.
It would have nothing to do with preventing Halo 5 sales, it's a news story that would rival the launch of a Halo game on a day that's supposed to be practically nothing BUT Halo news.
It's a big talking point.
Assuming it came to pass the way you describe, what effect are you imagining that would make it specifically about Halo 5?
Halo 5 will be big news regardless of whether or not it's theoretically released on a different date.
A $100 price cut will be big news regardless no matter what the date is.
What I'm pretty sure off in any case is that nobody that had plans to go to the store to buy a Halo 5 bundle because of Halo will not go and buy a Halo 5 bundle.
If the argument is just that having a big price drop for the holidays will have an affect on the holiday sales then disregard this post for obviousness, but then the specific timings are not very important, nor is the relation to the Halo 5 release date.