If the parody was obvious, why isn’t being a customer also considered parody? If it was a real hitman site, presumably it would be illegal for the site owner and not just customers.
I'm pretty sure you can claim that in a court. However, making an offline appointment with a hitman and then making them an offer and even making a first down payment for the service is probably difficult to explain away as parody.
just because the feds never go after anyone with money with their weaker laws doesn't mean their laws represent legality or illegality. you just still might wind up in prison for being indicted and convicted of something illegal.
this changes when you're rich and your rights matter
if they indicted her with a conspiracy charge that could be stronger. but I've seen those get dropped on appeal too specifically with some kind of parody/fan fiction defense.
so what's the difference? it's unresolved.