[Aoyagi]

"This can only happen because the key is on their server."

No, they can ask them for the keys even if they don't have them on their servers. And one would think that a likely response would be "We can't do that, we don't store the keys on our servers". Which is exactly what happened

https://www.theregister.co.uk/2018/03/21/telegram_ordered_ha...