I call bullshit, unless Sean and Whitacre put their money where their mouth is and report that noise. I mean, there's a complete system for whistle-blowing and anonymous tips. In fact, the IRS loves snitches so much, in some cases, they'll even give you a cash reward for that shit.
"The IRS may pay awards in exchange for valuable information that leads to the collection of "taxes, penalties, interest or other amounts from the noncompliant taxpayer," according to the agency's website. There are various types of awards granted, depending on the evader's income level and classification (business or individual). The IRS likely chooses to focus its efforts on these larger cases because they have a higher payoff. It has also been suggested that higher income individuals have been found to cheat more frequently and for higher sums of money, mostly because they tend to earn more self-reported income."