LOL! Never thought of that way but you are right.
But the hijacking that this guy was convicted of in the 1970's was politically motivated. Now, since his political side won and Croatia did ultimately get independence, they presumed that he would have no longer have any motivation to blow up or hijack another plane.
What surprises me is that they let him -- as a convicted cop killer -- go free. And that he was celebrated in Croatia as some kind of "hero" with supporters cheering him at the airport when he landed there.