  We revise the extended uncertainty relations for the Rindler and Friedmann
spacetimes recently discussed by Dabrowski and Wagner in [9]. We reveal these
results to be coordinate dependent expressions of the invariant uncertainty
relations recently derived for general 3-dimensional spaces of constant
curvature in [10]. Moreover, we show that the non-zero minimum standard
deviations of the momentum in [9] are just artifacts caused by an unfavorable
choice of coordinate systems which can be removed by standard arguments of
geodesic completion.
