Worked shoot, yeah... But Heyman was definitely speaking his mind.
A worked shoot isn't always scripted. And I don't find Heyman the type of guy to go out and read lines during a promo when he can just shoot. I'd bet if you asked Heyman if he was shooting during that promo he'd say yes to at least 80% of it. It might have guided a storyline, but the angle was for Heyman to have the disdain for Vince that he really had anyhow.
Also if it were scripted, Vince wouldn't stand there and say nothing. He knew the promo was killing.
That might be the greatest promo ever cut.
Nobody is saying it was scripted "word for word", but the angle was a work. Basically, they came up with the angle and Vince told Heyman to go out there, speak on all the shit people had always hated and said about Vince, and to tear him a new one. They did what was intended, to make a lot of people (maybe you being one of them?) believe it was a real shoot.
Also, he knew the promo was gonna "kill" before they did it.
If it was a shoot, you think Heyman would have had a job the next day? Definitely not. This wasn't the first or the last time there has been a worked shoot, or storyline, based on "behind the scenes" elements. They did the same thing at One Night Stand where Heyman did a worked shoot on JBL and Bischoff.
Nonetheless, an AWESOME promo.