They can redeem themselves by making contact with the flagger which is a lot easier if the flagger left a comment. The question is how long will it take for people to realise that the behaviour they've become accustomed to on other social media platforms is not the type of behaviour that contributes value to steemit.
There's a lot people will just have to un-learn, and that's going to take some time and personal adjustments.
The system doesn't order to the flagger to leave a comment, but it should. About the behaviour, I've noticed that people adapt pretty fast to steemit. Everybody have problems or questions first few days and there is no need to be strict to them
perhaps the introduction of probationary period