It's an argument over what ramifications for the security and the decentralization of Bitcoin removing the block size limit would have. Please don't spread Gavin's manipulative reframing. No one in that thread cares if less efficient miners can't "hack it", they all care what that would mean for Bitcoin. And if less efficient miners are part of what makes Bitcoin secure and decentralized then absolutely they need to be thought off when considering a hard fork type change of the protocol.