Leaving aside whether or not this is a valid way to attract top people, my suggestion is to rebrand the name - "cull" has too negative a connotation ("cull the herd").

So #1, I'm part of "the herd", and #2 this tool is being used to possibly cull me. Great. No thanks, I'll spend my time applying to a place that doesn't have a tool dedicated to weeding me out. It doesn't portray the hiring org or your tool very well.

I'd be afraid that you're turning off devs right away, before they even get to the site (which has the potential to turn them off even more). My $0.02