Why would a "Friends List Free-Trade" system mean that people would have access to your stash?
He is suggesting more of a clan bank tab. More so than a friend's list bank. Where this bank is where you deposit legendaries and other BoA goodies. He means that if he were to put something in the bank for a particular person in his clan, he wouldn't have to worry about someone outside the clan ninja'ing that item. It all seems like extra unnecessary work though, and I wish they would just open up free-trading to clan members and possibly implement a mail system. I have high doubts the latter would be implemented though.
edit :: additional clarity