Sure, they claimed that they turned it off, but there will always be someone who doesn't turn it off, especially when the bitcoin prices are going up astronomically. Rising electricity price doesn't matter.
Also, they hold up the "floor price" for electricity and push it up, meaning that electricity prices will never be cheaper.
Even if all of the bitcoin mining in the world happened in TX and 0% of them shut down it'd still just be 1/4 the normal power draw in the state (121 TWh vs 429 TWh), far less than the demand increase due to the cold or current production/demand gap.
Still keeps the floor price of electricity up as some would probably not bother turning off in the case of an astronomical bitcoin price. (Read the article Yahoo, they are in fact keeping some on!)
Also I'm assuming 429 TWh is when it's at full capacity. You have to quote the number for the current crippled capacity for a fair comparison.
429 TWh is average yearly usage, current "crippled" usage is 77% the yearly average usage, so 100% worldwide bitcoin usage would only account for ~1/3 the current "crippled" power delivery.
Worldwide mining would have to pull a hell of a lot more than ~1/4 (of TX) of ~1/10 (TX of the US) ~1/7 (US of world) to be setting the price floor of electricity.
A Bitcoin miner is not more or less efficient than a resist backup heater attached to a heat pump. I guess it would be bad for them to be somewhere that's not in a house, though.
All electric heaters are all considered to be 100% efficient. A bitcoin miner is an electric heater, not a heat pump. Although much more noisy, expensive and breaks more often, plus it requires an internet connection. So it makes more sense to get a normal heater. Mining bitcoin only makes sense on an industrial scale. Which is why these things are usually found in data center like facilities.
(Meanwhile heat pumps can go up to 300% efficiency.)
Sure, they claimed that they turned it off, but there will always be someone who doesn't turn it off, especially when the bitcoin prices are going up astronomically. Rising electricity price doesn't matter.
Also, they hold up the "floor price" for electricity and push it up, meaning that electricity prices will never be cheaper.