Hokaai! Get educated before you malign the judiciary.
The judge acted properly and correctly. And this is a good thing for SA, even if you don't like the effect in this particular case.
One cannot argue the merits in an urgent interdict (not in SA, and not anywhere in the world with a real legal system, and for good reason: consideration of the merits is reserved for the real case itself, where defendants have the right to defend themselves after thorough preparation). To obtain an urgent interdict (which is a really an interim emergency court order), you must show real and immediate prejudice to the client should the interdict not be granted. I don't know the facts in this case, but perhaps the FF teacher/client was already registered as a voter and therefore his lawyers could ovbiously not prove that he would suffer harm if the roll was closed - he was already on it. Urgent interdicts are very narrow and very specific to each case. I may well be that the FF action to interdict the president was a political stunt without any legal foundation, at least in the case of this particular client.
If you don't like rash, uninformed, and precipitous actions by others, start by curbing your own rash impugnation of the learned judge.