Don says that the salvage laws boil down to "if you find it, you got it." Salvage laws are very complex, and his expression of you find it you got it is not correct. As an FBI agent, he would know this because the FBI has jurisdiction over maritime laws along with the Coast Guard.
They say the NSA has the most satellite surveillance of anyone in the world. In fact, the National Reconnaissance Office is the agency that has the greatest satellite visual surveillance while the NSA has the greatest satellite eavesdropping.
The NSA team meet with Charlie in his office: top secret meeting, door closed, private. Next scene the meeting has moved outside, where the three are walking and talking, in public, with people all around within hearing distance, about the same top-secret mission. To finish, they remind him - with several outsiders in the frame - how top-secret it is, and that he can't even disclose it to the FBI. For sure the student walking up right behind them didn't hear a thing.
Since the smugglers killed off the salvage crew and Beghe's character was supposed to have died when his racing ship went down, there is no logical reason why they would not also have killed off Beghe's character when they were tying up loose ends as he was the only person alive who knew the guidance systems were on-board.