It's an interesting concept. Logically speaking there shouldn't be any negative influence among them to cause them to become "Depraved" even a little. They're all good people with good hearts, so there's little reason to assume they could just become corrupt from each other out of nowhere.
Meaning the whole trial thing is, likely, just a show of power. Raoul just wants to remind them that he's the one in control and that they should remember who exactly gave them their paradise.
My theory is that Raoul, wanting to destroy this sick/evil world, is now looking for faults even in good people.
That's because negative emotions like jealousy or greed are intrinsic in the human nature. Even a small thought like "I'd like to give my kid an extra piece of food" can be the spark that ignites the end of this uthopia.
Sure, we don't know how this place works, if it's able to avoid such a thing or if it's just a cage where Raoul can "control through fear" the survivors...for now, what is most likely it's that the mother is the glue that keeps the dream together.