Thinking about this some more, is there any reason why this would only be offered during HHN? A virtual reality experience, be it a haunt or anything else, does not scream out limited time only during the HHN event.
Not trying to be a Debbie downer or anything, hopefully it will be really cool and I'll decide I have to try it. Secondly, yes I do think I would be more of the opinion that if I pay money for a hard ticket event for a park I already have an AP at, I would expect I can do any of the attractions that are housed within the event.