The vacuum cleaner salesman was definitely at the wrong place at the wrong time bu it wasn't at the Gemini Club.
It was during the time in which Chris Rosenberg (and probably other members of the crew) had ripped off and murdered some Cuban drug dealers and their associates) Unfortunately for the crew some of the Cubans' friends had Chris' name and had pretty swiftly worked out just who Chris worked for. They demanded Chris' death as a weregild and threatened retaliation if it wasn't handled soon. So between the time that this happened and the time that he murdered Chris, Roy was very paranoid and on edge.
So when a eighteen year old of Puerto Rican/Italian descent dressed in suit and tie stopped his car outside of Roy's house, likely to get his bearings , Roy assumed the worst. He and his friends approached the car. The kid saw the men with guns and took off. They chased him down and murdered him.
Who is Chris? Demayo actually got strong armed by a gang of Cubans? I find that very hard to believe. Roy wasnt afraid of anyone, atleast that the impression I got from reading sins of my father.
Chris DeMeo- real name Harvey Rosenberg- was Roy's first recruit into his crew and as much as anyone the gangster to whom Roy was closest. According to most people who knew "Chris" he was not overly fond of being Jewish and thus used Italian sounding aliases. Chris even harbored fantasies of being "made" one day. Roy was a father figure to Chris as they were both misfits growing up who later became homicidal maniacs.
Because strictly speaking Roy was not supposed to be involved in drug trafficking he did not wish to risk news of all this drug dealing and ripoffs getting back to Castellano, who didn't like him in the first place. Also to protect himself Roy claimed that Chris had done the ripoff and used Roy's name without Roy's knowledge/involvement. So when Roy's captain, Nino, who also wasn't overly fond of Roy, found out about the incident and what the Cubans wanted, he told Roy to take care of it.
Bottom line Chris wasn't Italian and wasn't made so it was not a big concern for Nino. Nino was not going to commit Roy's group, Nino's other crews or the larger Gambino family to war over Harvey Rosenberg.
This is all from "Murder Machine".
