You’re in a thread that starts with the premise that this is a vehicle that the fbi/cia are going to use to distribute backfired versions of apps like signal, in which case no, it’s not an open and shut case of fraud.
It might be helpful to consider a simpler situation, where an FBI agent pretends to have a shipment of drugs which a drug dealer attempts to buy. If the dealer hands over money and doesn't receive the drugs, my non-expert understanding is that they can't then sue the government for fraud, presumably because of qualified or sovereign immunity.
The reason the government won't give back the money is that it will initially be evidence, and then subject to civil asset forfeiture. I don't believe that it matters that the item being bought was illegal, as if property law doesn't apply to illegal goods, since, in theory, if one drug dealer stole drugs from another drug dealer, the government could prosecute the perpetrator for both the theft and the possession of the drugs.
https://arstechnica.com/tech-policy/2018/07/judge-slams-fbi-...
People have this notion that the court system just blindly agrees with three lettered agencies, when in reality they tend to hate each other.