No, no it cannot.
If I were to grab a baseball bat, raise it over my head, and bring it swinging down at your head, would you be targeting me? Of course not, you have to be dense to think that the word "target" causes confusion, either that your just wanting Mark of Nurgle to be more effective for selfish reasons.
The idea that you are blaming this on the rulebook not providing a working definition of the word 'target' (laughable honestly) makes me grateful that your ilk don't run things over at GW. If you did than our BRB would be replaced by multiple volumes on par with the encyclopedia Britannica and cost thousands of dollars.
You actually have to think in this game, and cannot simply throw up your hands and proclaim a need for an faq to hold your hand every time a word is used that the BRB does not explicitly define. Give me a break.