I’m not buying it.
I think Oliver, or Maseo, somehow switched the alpha/omega virus with some sort of sleeping narcotic/anesthetics. Or maybe what Maseo gave to Ra’s was never the alpha/omega virus in the first place, and Oliver knew that. Maybe it was a fake Maseo used, in order for him to have leverage to join the League.
But, I do have to say. That Oliver/Nyssa marriage ceremony looked really real. So, unless Dustin Hoffman is about to break into that joint screaming or someone speaks up or forever holds their piece, I think they are actually going through with it.
That’s gonna be one awkward wedding night….