If Manafort shorted the IRS millions in taxes, he should be prosecuted, but so should Al Sharpton.
Right now, he is getting the full prosecutorial weight of the government, while other miscreants are either ignored or pled out for pennies on the dollar.
He should pay his taxes. So should everyone who have money parked off shore, but if they let his partner off, then he should get the same treatment. If Gates crime was considered unimportant than it is also unimportant for Manafort. But he should pay any taxes owed.