The reason we publish security information is to help people be more secure. Sometimes that includes information that could help bad people do bad things.
My point is very simple.
It's naive to think that hiding information that could help people be safe will prevent danger.
That's why I publish articles on security, alerts on bugs and possible exploits in programs, and techniques for writing secure code.
Now I'm not naive enough to think that no one will use this information for harmful purposes — hey, some people spider Safari, bundle up books into PDF collections, and sell them — but I'm going to encourage people to do the right thing. I'm going to help them find the information they need to protect their information and equipment. If they choose to do bad things with it, that's their problem. Hopefully enough people will have learned and applied the lessons that the bad people won't do much damage.
You don't know what kind of disclaimers this book has. (Spidering Hacks has a big disclaimer that says "Do the right thing. Ask first. Be polite. Be smart.") You don't know what's in it. You haven't read any sample chapters. You're making wild accusations without facts. You're misinformed about the copyright issue and you're tilting at a windmill here.
Hey, that's your choice. Have at it.
If you want to be morally consistent, though, you should probably also boycott everything O'Reilly's ever touched. It's a long list, though, and it includes this site.