The troll's men hired an Israeli private detective agency to try to find material to discredit the diplomats that negotiated the nuclear deal with Iran.

The agency was not looking for wrongdoing in those negotiations; apparently there was none of that. It was not looking for corruption; apparently there was none of that either.

Rather, it was looking for something irrelevant that would have happened long after the negotiations. Something that would not have had any implications about the deal itself. But it would have given the troll some eggs to throw at them, perhaps to create a negative attitude towards them and thus (irrationally) towards the deal itself.