Stewart Nozette, whom the FBI framed as Israeli spy, was not a random NASA scientist. Deeply in debt, Nozette continually overbilled NASA for eight years. He had been indicted and was awaiting trial at the time when the FBI approached him with an espionage sting.
The FBI, it turns out, tempted a man who would certainly cooperate with it. Very likely, Nozette participated in the sting knowingly in return for a lenient sentence on his fraud charges.
The only goal of such a sting operation could be to cause negative publicity for Israel.