The way I see it, if you're properly overfiltered then you can clean out a portion of your bio media and still should have enough to re-establish anything you lose without have too much of a mini cycle
Out of curiosity, has this ever been tested or validated? I've always wondered how long BB would actually survive when out of water or blasted with chlorinated water. Would be interesting to know, but I don't see how you'd know for sure unless you have some serious lab equipment. I guess it's one of those cases of better safe than sorry!