that person is turning 100% off.
Actually, I don't interpret it this way. Unless the seller is in dire straights, they may well continue to operate until they find a buyer. If they find a buyer, then their hardware will likely be offline until they have shipped stuff and the new buyer receives it. Once the buyer receives it, then it will return to service. Nobody will buy it unless they intend to run it. Nobody will pay serious money to purchase Bitcoin mining hardware with the intent of scrapping it.
You mentioned Euro as the fiat currency. That suggests to me a European seller. They could easily be selling to somebody with a much lower electricity price. That wouldn't be unusual at all.