I completely agree to that. So what‘s wrong with that demo? Having played trombone myself, I don‘t think a jazz trumpeter wouldn‘t play the way he demoed it. Maybe when he went up to the very high notes, it was a bit extreme. But the physical modeling (legato, glissando) makes even this quite realistic IMHO.
Just as a side note: the demo was done by the manufacturer, it would be very poor if they didn‘t know how to play a trumpet on keys, which is what the product is designed for, and apparently those who listened to it largely liked it. But maybe you don‘t like this kind of jazz trumpet playing...