It's a true fact!
So why would you want to befoul your good conscience by reading his virulently anti-capitalist and anti-American screed Capitalism in the 21st Century?
Obviously the apologists for the status quo are having trouble refuting his research on academic grounds, so they resort to pulling some unsavory personal details out of the hat.
Piketty's main point is that capitalism is in serious difficulty. What the status quo advocates are so afraid of is that this point, long considered self-evident to the serious left, is gaining traction among mainstream economists traditionally considered center and even right of that.
It's a classic and all too desperate Ad hominem.
Capitalism as we know it is in crisis whether Thomas Piketty abused his girlfriend or not.