That's the difference between "some people" and "company president." Come to think of it, I had the same experience at my last corporate job.
Any old dude might actually have to wait if he asked if you were busy.
That's part of why he's the company president, I suspect.
I recently created a webpage on cubicle etiquette for our company intranet; you click the "notify" button next to the relevant offense, it sends an email to the offender, that contains a link to coverage of the offense. It's very cool. I've only put it to use once so far, to enrage one of my cubicle neighbors. Let me know if you'd like a copy.