Absolutely - if you are sick, or even just fatigued, you have a responsibility to stop right there. But what I am saying is that if management then penalise pilots for this, perhaps because the 'law' allows it, then work-to-rule in ALL aspects of the operation is called for.
Unfortunately - as in the case of getting home for Xmas and to hell with duty limits - when work to rule does not suit the individual, he/she will break ranks. Savvy managers know how to exploit this human tendency.