Michael Posner is not an uncommon name so I am leery of thinking the name is that of the Chicago guy.
The reason why it is the same Posner is that first of all the mob wouldn't let an ordinary citizen pick off a cherry laundering biz like a casino on Aruba. That biz is perfect for the mob because, first, Aruba is on the drug transit line (and drugs are the biggest generator of revenues for the mob) and second, the drug biz requires a laundry operation.
Furthermore, the Mike Posner that owns the Excelsior is from Chicago.
If it isn't the same Mike Posner mentioned in the organizational chart, you can bet there is another Mike Posner working for the mob in Chicago.
In the very beginning, you exposed the criminal element in Aruba. Then came the 'necktie killing'. Seem like we are making a full circle here.