It is the duty of the acharya to voice his objection when he sees a threat to his 'matham'; in fact if more gurus had acted during islamic and christian invasions when sanatan dharma was attacked, temples were destroyed and mass conversions were done by threats and murder, history would have taken a different course. They never advised what to do and which course to take. Except in some rare instances, like Shivaji, the kings acted on their own with inconsistent and indifferent results. On the gnana side, our gurus have kept the tradition live and vibrant, but one the spread of non indic religions they have done pretty little. They failed to see and prevent the predatory spread of islam and christianity.