He is right - the only problem would be corruption in the judiciary. His plan might eliminate many of the "nuisance audits" of small businesses and highly compensated employees, but the IRS could still find a compliant judiciary when they wanted to target bigger fish.
There should, however, be a large majority of Republicans calling right now for just such a limiting of IRS power by the Fourth Amendment. That there is not speaks volumes about just what today's Republican Party is, and who they really represent.
Replacing the income tax with a national sales tax would also fix this problem. A national sales also makes nearly everyone
a taxpayer instead of the current income tax structure under which only 50% pay taxes.