The article didn't say that Frank Calabrese did it, only that there was a meeting between three different Families in Missouri, and that among the topics of discussion was the disappearance of Jimmy Hoffa. I personally find Mafia figures from Detroit, Chicago, and New York City meeting in a state like Missouri fascinating all by itself, regardless of what was discussed.
It’s not overly fascinating considering the Detroit and St. Louis families were connected by marriage and geographically back in Sicily. Also, Hoffa was connected to a St Louis lawyer with points in some casinos - Morris Shenker.
There’s some great wiretap audio of Joey Lombardo extorting him.
