After much wailing and gnashing of teeth, Capcom has announced it will implement split screen co-op in Resident Evil: Revelations 2 for PC. Better still it's accessible now, if you don't mind opting in to the open beta. The patch will also address some reported performance issues, according to a Capcom representative posting in the Steam forums.
The mode's unexplained absence caused a kerfuffle last week, resulting in refunds being extended. That was probably a wise idea on Capcom's part, since it was initially listed as a feature on Steam, though the official line post-launch was that the mode was cut "to ensure a stable user experience across a variety of different PC settings and devices".
Whatever the case, it's coming. The current open beta is missing some menu options and UI elements, as well as support for non-XInput controllers. You can learn how to access it over here, or read our review over here, wherein we describe it as a "so-so start".