He is correct in theory about power designation of the scope. He is also correct in theory that he should have never said anything.
He is not only correct in theory about the power designation, but practice as well. The correct designation of variable magnification range in a scope is written as "-" and spoken as "to."
Whole lot of jumping on this guy for trying to help people use the proper terminology designations. Kind of ironic to me considering that when I hear someone describe scope mag. range as "by" or "x" it makes me think they don't know as much about optics as they think they do.