In my experience women don't reject, they ignore. lol
As for the men reacting like that... I've seen it. Not often on dating sites, but quite regularly on sites geared towards finding sexual partners (in my case swinging sites).
I have found saying something like "Thanks for the message, but I don't think we'd be compatible" to be a bit more well received that an "I'm not interested."
Then there are just the people who don't care what you say. A no is a no, and that automatically makes you a "bitch who refuses to step outside your comfort zone to try." Those are my favorites... Not.