Thanks this is indeed very detailed, and gives alot of indepth information about it. Although most of the information is about the authors "Defending" segregrated witness, it still was very educational.
I still have some questions,
If 51% of the miners want smaller blocks they can have them today without BU. They can simply limit the size of their generated blocks -- the max mined block size is a command line option. Also, the max block size to accept is a constant defined in a header file. So 1 simple line of code needs to be changed for miners to ignore blocks bigger than N in all the "Satoshi-derived" clients.
Does this mean that 51% of the miners can call a hardfork for BU, ( I know that is not what they say in the quote, theoritical question)
whereas 95% is needed to activate SegWit?
I know it isn't a X vs X, but these ratios doesn't look right to me.