Commercial sale rules? Gay cake?
I seem to recall, from various instances of items being incorrectly priced, that the price tag is an offer to trade but there in no obligation to trade. So "I'll have this computer for 50 quid please because price tag" carries no force in law. If the vendor even feels that the prospective purchaser was rude and unhelpful then there is no obligation to trade. There are all sorts of reasons not to conclude a sale.
I do wonder, therefore, if you could refuse to take an order for a cake UNLESS the prospective customer phrased the order in a way that included a reference to something covered by anti-discrimination laws. That is, you can refuse without reason unless discriminatory terms are included in the order request, or even unless discriminatory terms are used in the refusal.
Wandering slightly back towards topic, could you refuse to bake a cake with a fiery cross and six hooded horsemen?
I can see that there is no easy answer to the GoDaddy issue. Can you be forced to trade in a way that adversley impacts your business? Activists often use a boycott to pressure a business not to deal with something they don't agree with, be it fast food, sweets, oil, animal products, whatever. I can't somehow see Harrods being forced to sell real fur because freedom.