As a public company, this bad news would certainly reflect in the stock price and market cap. If you priced the stock on future expected value, that future value would now be lower.
But Dyson is private. Not only that, it's 100% owned by James Dyson and his family.
A company with >£4 billion in annual revenue, employing >12,000 people. 100% owned by the founder and family. The owners are in complete control, with no fear of dilution.
Perhaps this is an unlikely story, to be able to grow a company to billions in revenue without losing equity-based control. Or maybe you're not a fan of Dyson's products, price point, or marketing strategy.
It doesn't really matter what you think, because the company is private. No pressure from shareholders. No pressure from the market, other than direct customers.
I'm not saying this is the model for every company, let alone most companies. But they started a project, decided it would be unprofitable, and walked away from it. They can do whatever they want, and they'll be just fine.