Read the article carefully, no one is being forced to sell in metric only, imperial measures may be used as well, but metric must be displayed as well.
It is possible to view this issue as a government insisiting that uniuform weights and measures be used, something that all but the staunchest libertarians would agree is within a government's authority. The metric martyrs are seeking a political cause and to score points against the EU.
I don't want to get into whether the EU is good or bad, it was the decision of the British Parliament to first join the EU and then to adopt the metric legislation. If the UK does not want EU regulation, it usually opts out (you can't spend Euros in Britain).
Finally, the last time I was in London, a publican was happy to serve me a pint of bitter, just like always!
When one reads the article, the grocers are arguing that this act was forced on them by unelected bureaucrats, however, But the judges agreed with earlier rulings that a European Union directive -- later adopted by Parliament -- requires loose goods to be sold in metric measures. Don't the Brits elect their leaders in Parliament? I thought they did, but perhaps things have changed?
And you're absolutely right about the fact that they are not being forced to give up the imperial system, but are being required to use both the imperial and the metric. What is the harm in using both systems?
My post was more to point out that Americans are complaining about something that the US Federal government requires of its own member states.