I have never read such rubbish.
A barrel roll has four distinct features:
* The wings are vertical at the horizon in the first quarter
* horizontal (inverted) at the top (well above the horizon)
* vertical at the third quarter (on the horizon)
* recover to the horizon, wings level, at the end.
All positive G.
QED
Did anyone say any different?
Yes, all positive G, but positive G at values that can be both greater and less than 1 (you can do the entire maneauver at greater than 1 g, but the G will still vary throughout).