I reckon in survival there should be an option to toggle fire spread and fire damage inside claims (just like explosions) - Cause burning stuff is always fun
I think the explosion destruction toggelability is a simple configurable option of the grief prevention plugin, I did not notice a similar option for fire but maybe I missed it. If its not a simple configuration change to enable such a feature I find it unlikely that this server administration would go through the trouble to code it into the plugin for you.