In any case, Al DeMeo said that Roy left all his jewelry and wallet ( I think??) the day he went. I'm not sure it would have mattered if Nino was there or not; he just had to know that whatever he was set to do that day, could likely be his last. I recall reading somewhere that Tony Spilotro did something similar?
Here's my 2 cents.
Why would Demeo take off his jewelry and leave his wallet behind unless he was summoned by a superior (Nino)? It had to be Nino.
It's hard to imagine Demeo leaving behind jewelry and his wallet just to meet up with the Gemini twins for the umpteenth time, or to meet someone outside of the Gambino family for coffee.
What it looks like is that Nino summoned Roy to a meeting to "talk things over". They served him coffee, and then Nino whacked him on Paul's orders. The Twins finished him off to show allegiance.
