Actually - I have his address and email from a board I sold him, I'll try and get in contact as it would be far preferable to preserve his hard work, I know he's a busy guy, he's mentioned that before so I wouldn't lose hope.
Please do! I PM'd him on GH several weeks ago and still haven't gotten a response, not that I'm surprised or anything. I really hopes this goes through though, this is honestly my favourite set that I have seen of all time. I've been waiting for a set like this to come out!
I got in contact with him a month or so ago and he has just been super busy. I wrote just now to see what he thinks about me taking over, we'll see what he says.
Thank you harlw, I don't really see it being ethical moving on with the set without his permission. 
Yes, definitely not. It's his copyrighted work, if he never comes back I may start from scratch with a new name but same basic color scheme as that was my contribution anyways.
There's not really much of anything that would hit copyright protection. The novelties are already commonplace enough that you could just redo them. The Green Screen logo could be up for trademark, though.
I always find the copyright discussion fascinating as it comes up here regarding keycaps but on other group buys, no such thing is ever mentioned (such as GMTO shoes).
As a designer I've studied copyright issues previously and you own the rights the moment something is created. All that's needed in a court of law to sue for infringement is documented proof that your version existed before documented proof of the accused violators version.
However, you are correct that the intellectual property would need to be, somewhat subjectively, unique enough from other similar intellectual property.
And yes, the unique parts of this set are easily replaced though my preference is for OP to get his priorities straight, put some kids up for adoption or something, and get this thing running.
