Unless you are saying that you take in all noobs that want to join you clan and grant them protection, stating "if you cannot look after your noobs" is a bit misleading.
We are not talking about clans being lazy here, we are talking about random noob friends coming together and forming a clan from the beginning. You can't expect new players to be able to protect themselves against nc griefers and if none of the established clans protects them, then they obviously quit after repetitive grieving.
However, being able to form clans to at least have that social component in place would help to keep people in the game.
You can add further restrictions, for example if you have one LEd person in the clan you cannot own an outpost. Or take it even further and say that you either need all with LE or all without. The latter would take care of the "clans being lazy" argument.
Actually LEd only clans would be an idea, it can fit from a role playing perspective as well.