As others have noted: it is difficult to counteract the effect of negative publicity brought against Samsung by Apple's accusations. Having Apple publicly retract those accusations is the court's way of trying to mitigate that.
Your analogy is deeply flawed. Apple had a choice as to whether to bring this matter before the courts and UK judge has no vested interest in protecting Samsung. There is no 'teacher' figure in this case; no more objective person involved in the case than the UK judge.
If Apple had no respect for the court's opinion, they should not have brought the lawsuit. In bringing the suit against Samsung into that court, they have effectively asked the court to pass judgement and agreed to respect and abide by the decision. The entire problem is that whoever is in charge at Apple believes they are in the right and that the court is wrong; the statement shows a lack of respect for the court and therefore is, in a way, a challenge to the court's authority. This is the judge's way of reminding them that they should respect the verdict and comply with it.
The only resolutions to this are Apple complies fully, or stops operating in the UK. The UK court system woud much rather get rid of Apple from the UK than allow a challenge to their authority to stand, and Apple would rather continue to operate in the UK than flounce out over a matter like this and lose the UK (and potentially the EU) market. Apple should have folded before, and should definitely fold now. The longer this silly game goes on, the more they have to lose.