Leftists have often demonstrated a refusal to believe the rules of the marketplace apply to them.
Doesn't really matter, one court case seeking administrative remedy in the nature of an injuction, and removal of obvious erroneous number and it replacement with proper statistical value is all it takes to put the crunch on your concocted scenario.
It only takes preponderance of the evidence in a civil case to achieve said relief, and since monetary damages are not requested only administrative relief the case would have everything going for it with the government on the hook to prove its numbers valid. Violation of expected Statistical varience from trend is more than enough to seek relief, and with evidence of arbitrary change of methodology from accepted practice will slam a grossly erroneous published value right into the bit bucket long before it could ever be implemented.
Your scenarios are merely speculative and have little to recomend them or even suggest a rational basis in view of historical processes and modes in the publication and implementation of statute sensitive statistics. Nor do they take into account of the very real and useful authority of the court to set bureau regulation right when such exceed the boundries of legislative scope.
Now if Congress were to enact such a gross change in methodology to specifcally implement such shenannigans that would be another matter another matter, but we are subject to that right now so your imaginative worries mean nothing through extension onto a new statute. The statutes are subject to legislative change now an can modify the current law to achieve severe magnitude changes in tax law now without risking the least in challenges before the courts.
But mere official error, malfeasance, misfeasance or outright fraud will not fly on adequate challenge in the courts. And challenge in the courts on the part of Corporations, businesses, and class actions of individuals potentially effected would arise overnight on the first view of substantive changes wrought by bureaucratic fiat changing the effect of statute outside of the legislative intent of Congress. Statute severley contols the scope of implementation via bureaucracy to the intent of Congress as expressed by statute and constitutional limits on official authorities.