If I were attempting to create a less "captured" Wikipedia alternative that's what I would do - start from there and try to keep it synchronized while hacking at it slowly, instead of taking a from-scratch approach.
There have been many Wikipedia forks, but all have failed, because 99% of the work is in doing uncontroversial stuff that most people are fine with, and 1% is in controversial "captured" areas. If you fork the whole thing in the hope that you can fix the 1%, you will have to find a way to do the 99% bit.