Penalty for leaving clan

I am not sure if this have been already suggested, but i would think that some kind of time penalty for leaving clan would be a good way to stabilize the situation in many clans, expecially for those clans which are not in so called "top". I think its a common problem for many clans when some guy joins the clan, requests troops, plays like 10 minutes, then tells that everyone in this clan are noobs, and then leaves. Its very annoying when that kind of persons get in preparation day for war, and while preparation - leaving. This would be awesome if for example after leaving clan, person can't join another clan for a week (for example). If this could be added, then also would be good some kind of activity info in the clan which everyone can see (last time when player was active) and some kind of clan lobby chat, where every player can send a message to your clan, to ask some questions about clan ierarchy or rules, to choose clan more accurate and wisely.