SE themselves don't sound sure when the PC version of Nier will be ready, so there that's your answer instead of your Sony moneyhat conspiracy BS.
A game not being ready does not mean that you cant advertise for it. Especially if the adverts and logos are already made and where already on published adverts that didn't have release dates.
Games get advertised for years before the game is even in a remotely ready state. This is common.
Again, it makes absolutely no business sense for them to remove marketing for this game, for a huge potential install base, especially considering that the material was already made. Unless a marketing deal was made at some point after the adverts and marketing material where also made that offset the cost.
I said earlier that two things that Sony might be factoring into their decision to do this is, they are flush with cash and are known more and more lately for their "Niche" games over the competition so they want to reinforce that in the minds of their audience. Also, they could see that this game isn't going to be very hard to run so more people with lower spec PC's will be able to run it, therefore meaning more potential lost sales for their platform. As well as seeing the recent boon in Japanese games sales on PC.
So there are some potential reasons. No one is going to be able to know for sure, however, like I said, it would make absolutely no business sense to remove marketing (talking about stuff without even a release date) for your product without some sort of compensation.