[Charles Henrickson]

Was he really named William "Rivers" Pitt at birth. . . ?

No, he added that when he started his blog. See his essay, "A Rivers Runs Truthout."

Seriesly, though, I think the "Rivers" is genuine, seeing as how his dad is named Charles Redding Smith. The appellation doesn't fall far from the tree.

[Charles Henrickson]

seeing as how his dad is named Charles Redding Smith.

Typo. Charles Redding PITT, of course.