So, misconduct by law enforcement officials doesn't matter if it doesn't involve physical violence? Your dislike of money and moneyed organizations in politics do not justify the people in those organizations having their rights violated by selective enforcement of the law. If that's not what happened here, why all the stonewalling and disappearing of evidence? Would you accept such a lack of cooperation with an oversight investigation from a local police department even if it didn't involve someone being shot? How about an organization like the NSA or the FBI? If so, I guess I can commend you for being consistent, even though I disagree with the weight you give to law and order - or natiional security - over civil liberties. If not, why don't you hold the IRS to the same standard as other law enforcement agencies?
If there was "deliberately lying on tax forms", rather than misinterpretations, or merely differing interpretations of vague and complex laws, then yes those need to be investigated. It does not, however, give IRS agents a license to act with impunity any more than a robbery committed by Michael Brown gave Darren Wilson a license to kill. Again, if there was no wrongdoing the IRS should let the investigation show it and stop the cover-up.