I imagine there are psychologists on the production team to support the camp mates before, during and after the show. Camp mates probably see them routinely throughout their time in camp and they are available on demand as well. JL probably knows them very well by now.
A few questions to get Nella thinking about her behavior in a routine session would be enough to make her realize what she says and does is visible to millions and not just camp. The show can't afford anyone to be cancelled as a result of appearing as no other celebs would want to do it in the future or they would be so reserved the show would be dull and no one would watch.
They need to have lots of drama in camp but nothing that permanently impacts a career. So Nella gets a nudge to make herself more likable and be on her best behavior. But I reckon her true, young, fame hungry, snowflake self will pop out again soon.