Silverfish breaking blocks when "mobGriefing" is set to false

When silverfish crawl into a block and makes it a silverfish-block, it get's destroyed when the silverfish exits the block again, even if "mobGriefing" is set to false.
This is not wanted as it makes silverfish able to destroy adventuremaps, and thereby it becomes a mob that is not usable for map creators.

My suggestion is to turn the block into it's original ID when a silverfish leaves it when "mobGriefing" = false.