You don't have to obligate them, if the CEO has a notice period but wants to leave early and the company is happy with that, they can always waive the notice period.
I'm so glad I live in the EU, where you generally don't see clauses like this (except within probationary periods).
In the Netherlands at my last job, because I didn't hand in my resignation 'before the end of the month' (Dutch law) - I handed it in on the 1st of the next month - they tried to make me work an extra month's notice (so effectively 2 months instead of 1). They were resolute about this, despite me leaving because I was very unhappy working at the company.
New York is a "at-will" employment state. Unless otherwise specified, both parties can do as they wish (give a 1 day notice, for example. Though that would look very bad for future employers...)
http://en.wikipedia.org/wiki/At-will_employment
I'm so glad I live in the EU, where you generally don't see clauses like this (except within probationary periods).