You're NOT violating him
For heaven's sake, why do you think some artists and writers are such pack rats? They save everything! They file it, label it, catalog it, put it in drawers, stow it in suitcases, etc. etc.. For what? So they can have a big bonfire on their deathbed? NO! So that tangible elements of their artistic trajectory through life remains.
As for Kafka, I think it's a cop-out to DEMAND that SOMEONE ELSE destroy what is left behind after you die. If he didn't want it around then A) don't write it down, or B) burn it before it's too late!