I'd wager she didn't say anything because she didn't want him to get hurt. Sure, something could have been done about Shinji, but what about Zouken? What's someone like Shirou supposed to do about him? He's be dead before he's be able to do a thing.
I shouldn't even have to mention the fucked up shit Zouken put her through as a child. That itself would normally drive someone insane, I find it amazing she can still function in society. You wouldn't really want to involve anyone in something like that and most people wouldn't be able to do anything for her anyway.
And let it be known that I don't even like Sakura as a character, I find her annoying most of the time. But I wouldn't call her a whore, by any definition of the word.