Yep. I'd expect them to receive a cease & desist letter within the day. The real Slack doesn't have a choice if they wish to protect their trademark.
Jeff Morris Jr. here (founder of Slack Chats).
I've spoken with the Slack Team and they are big fans of this product. In fact, I've had several team members email me to thank me for building this product.
I included the note as the top post to clearly state that this isn't an official Slack product.
The site drives traffic to Slack and I do not make a single dollar off of it (despite many offers from advertisers).
Hope this helps!
Jeff
[1] http://thenextweb.com/insider/2015/03/24/slack-is-quietly-un...
Again, I am not an employee of Slack and do not want to speculate but that's my best guess.