grumpy's post succinctly sums up the legal situation, which is what the court uses to form its judgement -
// You're quite right SP1814 bigotry cannot be tolerated.The judgement is that they would not print the message because of their beliefs not that they discriminated against the customer. //
It's an important distinction, but a vital one in legal terms, that the refusal was not made against the customer's orientation, but the message he wanted printed, which is not the same thing.
All the nonsense about it being a set-up and 'virtue-signalling' and so on, is so much irrelevant guff, the verdict was decided on the application of the law.
I said at the time that a degree of pragmatism would have avoided all this unpleasantness, the couple could have offered any number of reasons not to fulfil the order. They felt they had to make their beliefs and offence known, attitudes which do not sit well with running a business serving the public.