I never really cared that tumblr had porn in the first place. So I will have no idea whose these people are and where they will go but I don't think I'll be affected by their presence?
There are some things inherent to Hubski's design the slow proliferation of this kind of thing. First of all - hubski doesn't host anything but the text... so I guess if someone started posting a bunch or erotica based on children we could/should get concerned. I remember very clearly stumbling on a post years ago with a title of something like "I wonder if we'll find a home for like minded people here" and it was a terribly graphic photo of a victim of violence. I don't remember if I replied to the post, but I certainly reached out to mk on the side and I believe he deleted the post. Eventually - if you post a bunch of stuff that people find objectionable, you get ignored into oblivion.But if you are in an online space allowing user content I'd start preparing for a shitstorm