ash.1111
Perhaps the passenger wasn't so wrong & the crew member wasn't so right.... Turbulence & airspeed very much are an issue. Just like driving your car along a rough road surface, going slower helps to reduce the jarring on the car.
§ 25.1517 Rough air speed, VRA.
A rough air speed, VRA, for use as the recommended turbulence penetration airspeed in §25.1585(a)(8), must be established, which—
(1) Is not greater than the design airspeed for maximum gust intensity, selected for
VB; and
(2) Is not less than the minimum value of
VB specified in §25.335(d); and
(3) Is sufficiently less than VMO to ensure that likely speed variation during rough air encounters will not cause the overspeed warning to operate too frequently. In the absence of a rational investigation substantiating the use of other values, VRA must be less than VMO—35 knots (TAS).