There is a zero percent chance Apple shareholders would allow dropping the second most important market, that's just delusional. Apple is a public company, what argument would they bring during the shareholder call? "We don't like that the EU forces us to make batteries replaceable, so we only sell via the UK now" - does that seem like something that would go over well to you?
And in regards to your link: as much as some of the UK would like to believe otherwise, the EU is a significantly more massive market.
No the argument would be: ‘we can’t sell the products we want to make in this market, so we’re not going to.’ This isn’t some kindergarten ego fight, it’s about Apple making the products they make and not being forced into making products that are not Apple.
If Apple shareholder calls worked like you think we would have all these things every know it all pundit has been demanding for a decade. But we don’t. Because shareholders know and trust that generally Apple does know better.
In reality however, Apple complies with a variety of government regulations already, around radio, power consumption, safety, and so on. This new battery regulation is just one more of those, and just like before, Apple will adhere to it. Why? Because Apple and the shareholders like making money a whole lot more than not making money.
And in regards to your link: as much as some of the UK would like to believe otherwise, the EU is a significantly more massive market.