This is obviously untrue, since at the beginning, even the weakest flunky would still tower above Duan Yu energy-wise. Out of all the characters in all the novels, only Abbot Fang Zheng in SPW has been shown to be able to directly resist the effects of inner-power absorbing arts, though high-level fighters can retain enough control to knock the absorber away.
Duan Yu only learnt a portion of the skill, so that energy would only be absorbed if it came into contact with a particular pressure point. Had he learnt it all, he should be much more versatile.
By comparison, Lingwu Chong, who learnt a much-degraded derivative of Duan Yu's skill, was able to absorb energy from all four limbs while hoisted in the air by the 6 Peach fairies, and could also absorb energy just from sword-to-sword contact.