I took it that the other attendees at Roth's birthday party included investors. After Michael made his observation that the rebels could win,Roth made a point of pulling him aside and telling him that he preferred to talk about it when they were alone. He didn't want them scared off.
In addition to possibly establishing an alibi in the event of Mike's murder in Cuba,Roth also wanted to demonstrate stability and continuity in his business holdings.
This was basically the underworld equivalent of a corporate shareholders meeting.The CEO gives his recap to date,and then lays out the prospects for the future,including the plans for dealing with any potential negative situations.