Core numpy is really weird, and has really sloppy logic around higher-dimensional objects. I've a module to work around lots of the warts. If somebody has smarter versions of intersect() or in() or whatever, contribute!
Apologies if this was explained in the talk, but why not upstream your changes to numpy?
No real good reason, honestly. I wasn't feeling positively about numpy devs at the moment, and didn't want to negotiate getting the code in. The library is solid though, and should be merged. I need somebody to pester me about it, to actualy work on that today.