In all honesty, I think twitter is for twits.
By all means get an account if only to prevent people squatting on the name and using it for negative PR purposes, but have your CEO guy clearly tell his friends and family that he has no real intention of using it.
Then get him to right up about 200-300 lines of shit he might say in his daily musings, then get a cron job to post one at random each day. After a year, no one's going to notice them being recycled.
Finally, get an intern to check that crap once every 2-3 days and respond to shit that's DMd, and only bug the CEO if it's something he can't answer himself, like a request for a press interview (although what hackneyed douche journalist would do that over twitter instead of calling the office?)
He's the CEO. He's supposed to have better things to do with his time than use twitter.
With all that said, if he likes the idea of using it then let him have an account and use it.
It will make him seem more accessible, and the company more responsive to public commentary.
Just don't tell him to get all bawbawbaw if he only has 18 followers that aren't employees.