But that's his job in this case.
Schiller is the closest thing to a star witness the jury will get at this trial -- as he was introduced to the jury on Thursday, Apple's lawyer mentioned that he sometimes appears on TV -- and he's also likely to be one of the most colorful.
He described to the jury how Apple came to develop the iPhone, calling it a "bet-the-company product" that could have bankrupted Apple had it not been a success. And he relived the "electric" atmosphere at Macworld Expo 2007 when he used the iPhone to chat with late Apple CEO Steve Jobs at the phone's global unveiling.
He also recalled his first response to seeing both the Samsung Galaxy smartphone.
"Wow, they completely copied the iPhone. It was completely astonishing and shocking to me," he said.
And in response to the tablet, "This was another example of Samsung copying Apple products."
The message to the jury was clear: Apple had risked everything on a successful product that redefined the mobile phone industry; in reaction, Samsung had figured out what consumers liked about it and copied those parts, and the company has to pay for that.
The case is 11-01846, Apple vs Samsung, at the U.S. District Court for the Northern District of California.
Martyn Williams covers mobile telecoms, Silicon Valley and general technology breaking news for The IDG News Service. Follow Martyn on Twitter at @martyn_williams. Martyn's e-mail address is firstname.lastname@example.org