Aside from the possibility of having a bear tangled up in cord, it may also give the bear something to grip, and drag your canister further than he would normally bother with. If Mr. Bear finds you canister, he tries to get in for a while, gives up and looks for an easier meal - it's sized so he can't fit it in his mouth. The worries are overblown, I've been using bear vaults for years for hiking and for food caches... it's never been touched.