I really wanted to fake the experiment in order to convince people about the dangers of failing gatekeepers, wouldn't it be better for me to say I had won? After all, I lost this experiment.

If you really had faked this experiment, you might have settled on a lie which is not maximally beneficial to you, and then you might use exactly this argument to convince people that you're not lying. I don't know if this tactic has a name, but it should. I've used it when playing Mafia, for example; as Mafia, I once attempted to lie about being the Detective (who I believe was dead at the time), and to do so convincingly I sold out one of the other members of the Mafia.