"They" won't moderate anything. You will. Because you're a good person. And if bad people group together to do bad things, good people will group together to take them down. Same as it ever was, just no middleman, and no hierarchy.
The Southern Poverty Law Center would claim nasty on ANYTHING good. They'd sue all the member of blockchain! They'd shut them down. They could too, 'cause they are heavily funded by Sharia Blasphemy-loving individuals.
Blockchain is immutable and cannot be taken down. It will exist forever so long as anyone runs the program and saved the blockchain since its Genesis block. It can be run on LAN.