A little perspective on some of these comments.
First, many of these actions are a direct violation of the IRS code and likely state and federal laws. There are very specific rules about both private benefit and inurement (similar, but different, topics - google it). The IRS's main tool is pulling the organization's exemption but there are also intermediate sanctions such as an excise tax on the excess benefit. Just like your local police department, the IRS does not have the resources or inclination to go after after person breaking the law or violating a statute so very possible you will see no action here (unless the IRS is provoked or encouraged - but the public, a congressman, etc.).
Second, state law (Indiana law in this case, I assume) governs the actions of non-profits. Safe to say they have rules on the books about proper conduct - it appears many of these allegations would violate the spirit if not the letter of the law. This is especially true if USATF is seeking charitable donations.
Finally, the sales tax matter is serious. It is clearly an action contrary to the Indiana tax laws that allow USATF (a charity) to avoid state sales tax for transactions that further their exempt purpose. It is serious, even though not a large amount, since it might indicate a deeper issue. If Max is buying "stuff" on the USATF account for that racing team or other businesses, it is likely breaking the law even if that entity reimburses USATF. Along these lines, using USATF "tax supported" offices and warehouses, phone system, computers for the non-exempt purposes raises IRS, state law and sales tax law problems (the trifecta of non profit fraud problems).
I see comments about whether Max's salary is too high. Some think it is okay to have a ultra-high paid executive and others comment about the size of the organization. The IRS cares a great deal about this matter. The 990 even has questions meant to guide the charities in its behavior. Google "501c3 excessive executive compensation" and you will see plenty of conversation including stories about the Fiesta Bowl, evangelical organizations, hospitals, and so on. The fact that peer companies like the other big olympic companies pay high but not ultra high comp to their CEOs may lead the IRS to an excessive compensation case (again, the most likely penalty is called an intermediate sanction and could be an excise tax).
The outrage by most on this board will likely melt into a malaise and then forgotten. Perhaps the athletes will see themselves as victims of a fraud and wonder how the spent money would have been distributed to programs that address their needs (which is, by the way, the mission of USATF).