[treetopsandroofs]

“My pet peeve: improper use of “that” instead of “who”. Example:
He was the man that robbed the store.”

Again FWIW, this explains it the way I learned it 35+ years ago....

It is entirely acceptable to write either the man that wanted to talk to you, or the man who wanted to talk to you (3). [emphasis added] - See more at: http://www.quickanddirtytips.com/education/grammar/who-versus-that#sthash.PJOO46YJ.dpuf

Source:
http://www.quickanddirtytips.com/education/grammar/who-versus-that

[econjack]

From your second source: The quick and dirty answer is that you use who when you are talking about a person and that when you are talking about an object. Stick with that rule and you'll be safe.

which pretty much confirms what I was saying.