Just grab these IP packets when CA comes to validate that you own that domain. Perhaps EV could solve that to some extent but it is never mandated.
Even if you tried to put any stuff into WHOIS to mitigate this, your hoster can serve any bullshit on this channel too.
It does look very bad and SSH approach to certificates is just infinitely better. If Jabber used SSL keys instead, they will be alerted immediately.
Come to think of it, your hoster can also find ways to steal keys directly from hardware, though.
It's like SS7, or SWIFT. It's not bold to claim that all public phone networks and bank transfers are insecure, it's just a fact. People who know what they are know they're vulnerable.
As an aside to the design issues, social engineering any of the thousands of organizations involved with issuing certs (not just CAs) is trivial. A bored teenager could get certs issued for most domains by using nothing more than a telephone or e-mail. But that's cheating, so I don't count it.