He is arguing that if BTC price went up 100x, it would be so much more profitable to attack it that it would require a comparable increase in the hash rate (and

He is arguing that if BTC price went up 100x, it would be so much more profitable to attack it that it would require a comparable increase in the hash rate (and therefore electricity usage) to deter would be attackers. So either hash rate increases, or BTC loses it's security. Or the same thing, but stated the other way round, as the profitability of mining increases (due to price rises), more participants are attracted to the market, raising the hash rate and bringing profitability of mining back down to the marginal equilibrium. Essentially the argument is that cost of mining/attacking is always in rough equilibrium with price, because whenever it isn't someone will take advantage of that in a way which will have the feedback of narrowing the gap again.