I put some comments here than changed my mind because it sounded a bit negative but here I go again..
If you are drying a down bag, hanging a wet bag by the foot box like that can put too much pressure on the lower baffles causing them to fail.
A better way is to use something like a portable clothes line (or indeed a standard clothes line...) and drape it over that spreading the load.
(that is why you are meant to use the cotton bag to carry your wet sleeping bag from the tab to outside)
As a side note, a bag will dry faster black side to the sun.
Franco