you can't really deny all of the people who benefited from linus pauling's work and dr. abram hoffer's work, and the countless people who took megadoses of c to ward off the effects of chemo.
at the very least docs who prescribe ascorbic acid should warn people, or people should be more discerning about what they choose to put in their bodies and discontinue immediately if something is amiss -- whether this be vit c, foods, or prescribed medications. i think people need to be more visceral in general. animals are much more in tune with their systems than humans, and there is really no good reason for this as we also possess very strong instincts.
even with Antibiotics , which in my opinion, are far worse than ascorbic acid, there can be benefits to some people. in healthy people the flora change is supposed to be temporary and is supposed to regrow in short order.
perhaps a good question is 'why do you have problems with bowel flora?'