I dunno, it was a conjecture, I'd never heard of strongly connected components either! Sounds right to me though. I'm fairly certain the OPs book will go on to prove that in due course.
I think strongly connected is an equivalence relation and those partition a set into disjoint subsets anyway.
EDIT: Proof here http://www.ics.uci.edu/~eppstein/161/960220.html
Edited by Paradigm Shifter, 30 October 2013 - 08:18 AM.