Depends on what you mean by "approve". Would I be satisfied if someone started using this strategy in-game? Probably not (depends on circumstance, as war can do funny things to people). Would I be satisfied if the devs said we absolutely cannot do it? Definitely not. It is infinitely more profound when someone chooses to set down their weapon of their own volition than it is to have Big Brother take it away from them.
Getting back on topic, tying one's ability to harm a sanctuary to skills would be interesting (like an anti-druid skill set to combat druidry, etc.), though it'd also make sense to tie this stuff to the nature/industry slider.
Edit: If the devs prevent us from ever engaging in this strategy, then they should remove all the black skills. We'd wind up with a different game which I probably would be satisfied with albeit for different reasons.