When Trustico decided to light their whole business on fire they sent people's private keys to the root CA they were reselling, triggering all the relevant certificates to immediately get revoked.

But if you were like "LOL, use keys you picked instead of my own private keys I tell no-one? Do I look like moron?" then no matter how stupid, greedy or incompetent Trustico were they didn't have your keys and couldn't give them away on purpose/ accidentally.