I'm not so sure about this judgement at all.
I think this might prove widely problematic. But I need to read more.
I think it is one thing to be able to personally refuse to state or support lies/ provable untruths, but I would have thought this case would have thought come under Article 9 Freedom of thought conscience and religion, where the bakers could refuse the slogan on grounds that it is at odds with the practice and observance of their religion.
Article 9 provides a right to freedom of thought, conscience and religion. This includes the freedom to change a religion or belief, and to manifest a religion or belief in worship, teaching, practice and observance, subject to certain restrictions that are "in accordance with law" and "necessary in a democratic society"
I can't see anywhere in Article 10 that there is the right ‘not to express an opinion which one does not hold’.
When WomensPlaceUk were in the Lords today their objections were supported by the Baroness Winterbourne under Article 9, not 10. This would come under freedom of thought and conscience I would expect, as would the "right not to have to express an opinion one does not hold."
The judgement was quite an upset I have read.