I guess I can't say for sure independent of the articles I've found which say such at best, and are vague at worst, but it seems the company they are partnering with, Chain[1] is pretty committed to building on top of bitcoin's blockchain.[2]
It came out later that everyone just assumed they were using Bitcoin because they were using OAP. I can't find the source at the moment but I'm pretty sure someone from Chain or Nasdaq mentioned that they weren't using Bitcoin at 20/20. Unfortunately all I can find in /r/bitcoin is people confirming they aren't and not the source.