I don't agree with this analysis. If mining becomes 100x more efficient, and the difficulty goes up 100x, you have not gained any security. The security comes

I don't agree with this analysis. If mining becomes 100x more efficient, and the difficulty goes up 100x, you have not gained any security. The security comes from the amount of money spent on energy to mine the current chain, and the fact that someone seeking to mine a parallel chain to double-spend (or whatever else) would need to spend a greater amount of money to mine even faster. So if miner's collectively spend $X on energy to mine the next block, it doesn't matter whether that buys them one hash or a trillion hashes - someone looking to mine a parallel chain would just have to spend $(X+1) at the same hashes/energy efficiency.