Members of the Horde are smart enough not to challenge a character like Sylvanas to mak'gora. Not only is she undead but she's an undead who is sly and would do something to achieve victory. I fully expect Saurfang to do this to show the Horde how much of a snake she is.
I argue because I disagree with you. If you turn out to be right then the Honorable Horde will be fighting against the odds but personally, I just think the numbers are larger than we think on who is against Sylvanas.