If this was not a PR move, but a desire to get a sense for work conditions, real problems, etc, it would not be publicized.
And it wouldn't work. I don't think a lot of people would be comfortable sharing real complaints with the CEO who parachuted in for a single shift. It will probably end up being a bit of a Potemkin village situation. The shift will probably be filled up with the highest-motivated, most ass-kissing employees, whose focus will be keeping the CEO comfortable.