You answered the wrong question. What does losing troops when you leave accomplish?
xLosing troops would keep the clans that are looking for actual members and not experience for donations, to be able to do so! The penalty would only have a two hour timer in which it could keep track of whether troops were donated! And if the player leaves in those two hours or is kicked then they lose troops if kicked then they also receive the two hour penalty! Plus as I said if they already used the troops before leaving then they get a two hour penalty!
Losing troops is supposed to curve hoppers away from those looking for members and not just donating for easy experience! And those looking for experience would have more hoppers to donate to!
At higher levels donating troops to people who plan on leaving may not be a big deal, how ever it's not just higher levels with clans! If it was you wouldn't receive a town hall until level 8! The option could have a check box in clan edit or supercell could implement it in invite only and open clans! Both options would need to be visible in clan description so that, those looking for troops would know which clan to go to!
Sorry if this post is a little sloppy I have a separate thread that I have been editing in order to keep the idea in a neater way versus scrolling post to post trying to get the whole idea!
Sorry I know I am not supposed to make a thread of one that already exist but if I had an option to make it private I would but I have to order the ideas in order to understand it fully!