You are just giving an example of how lack of "coherence between means and ends" leads to failure.

A military occupation (means) is not an effective way to achieve lasting control over the civilian population (ends) unless much of the population is already on your side, so it is foolish to try to use those means to achieve those ends.

Russia has also been hurt quite badly by lack of moral restraint in the war against Ukraine (which in the context Clausewitz used it I believe means more whether you have rational control of your actions than whether your actions are "good" or "bad"). Attacking civilians is usually extremely ineffective at achieving anything other than making leaders feel good that they are hurting their enemies and usually just hardens the enemy's resolve to continue fighting.