As explained in the first paragraph of the plugin homepage, Blackhole traps bots that follow the hidden link and fall into the trap. So the plugin traps all bots except bots that do not follow the link and fall into the trap.
I hope this makes sense, let me know if I may clarify any other details.
Thanks, Jeff!
So if my robots.txt looks like this:
User-agent *
Disallow: /?blackhole
Disallow: /
And I remove all the whitelisted Bots in the settings.
All good bots will not crawl and bad bots that follow the hidden link will get blocked?