The absurd thing is, why tf should a custodian be allowed to use my stocks as collateral in the first place. How does it make any sense, and how are the people who enabled this not under constant public outrage?
Discussion
It makes kind of medieval sense to me. If you rented cattle from your neighbor and went bankrupt, I would just take the cattle and make you reliable for the loss. You control it, so it‘s your problem. This may not work anymore for corporations, because you cannot really go after legal bodies with limited liability.