"No bid" doesn't mean you log into your broker and see literally no bids for your gilts. As you rightly point out, primary dealers are obligated to supply a bid

"No bid" doesn't mean you log into your broker and see literally no bids for your gilts. As you rightly point out, primary dealers are obligated to supply a bid and an ask in the gilts markets, and in return receive various privileges in the same markets. But obviously that doesn't mean that they are obligated to absorb billions of pounds in selling pressure (due to large pension funds needing to meet margin calls) without significantly moving prices, which is the question at hand, and that's what the author means by "no bid".