Well, the acquisition of circumstantial evidence that would convince a jury in either a perjury prosecution or murder prosecution can be quite a hurdle.
With Michael's sworn testimony on record at the Senate, and with Frankie's sworn testimony also on record, it'd be easy for a US Attorney to bring in a perjury indictment. Supportive circumstantial evidence may have been less convincing. But the issue is: once the case is brought to trial, conviction or acquittal rests with convincing a jury, not on case law. The real benefit is to bring the case to trial. Even if the jury acquitted Michael, he'd be seriously damaged.
Also, I don't think Michael had any license associated with gaming. In fact, I don't know why he would have.
I inferred that he did have licenses in his name or in the name of a corporation connected with him. Geary said,
You [emphasis added] own or control three hotels...the licenses were grandfathered in so there was no problem."
