Indeed. The flag has to be removed or it has to be upvoted by the same amount of vesting power. Sorry to hear what happened. I checked out the post and I can't see anything wrong with it. IU'm unsure why you got flagged but there must be a reason. Contact Dan through his steemit chat channel and also the steemit-abuse-appeals channel. The community will help you solve your problem. Dan isn't the only person with power on Steemit and other whales are more than happy to go against him if need be.
If I was to be critical though, the only reason I could see your post being flagged is because @dantheman didn't like it. I don't know why but as you said, barrycooper mentioned this flaw in the design. It's the reason why I hate how the negative reputation system works. It should be a majority of negative votes, not just one vote from someone with a lot of power.
RE: Why Was My Post Downvoted? - An Open Message To @dantheman