Hmm. So judges can now just...rule on whatever they want, whenever they want? That how it works?

No. If they rule incorrectly, their rulings will be overturned. During the time when the court order is in effect, you have a legal obligation to follow the court's order. Even if it's overturned later, it is a wrongful act to defy a court order while it is still active. Because that's how the rule of law works - a court order is valid until it is overturned.

Except this scenario is the reverse of the above. The judge is saying, 'Yeah, my TRO was bad but you should have followed it anyway'. This is a ticking bomb.

That's how the law works. It's not a ticking bomb. The whole point of TRO's is that they impose obligations on the parties while the merits are being worked out. It's known and anticipated that TRO's might end up not being the right answer - which is why they are Temporary Restraining Orders, rather than the court just issuing a summary Permanent ruling right at the beginning of the case. The reason we have TRO's is not to work a final disposition of the case, but to force the parties to preserve the status quo so that when the case is finally decided, the parties haven't been irrevocably harmed during the pendency of the suit.

So if you and I have a property dispute over which of us is the owner of a valuable piece of pottery that you have possession of, the judge may issue a TRO telling you that you can't destroy the pottery. Not because the judge is deciding right then that the pottery belongs to me (after all, if it belongs to you then you can destroy it if you want). It's to protect the party who might win the case from being unavoidably damaged during the interim. Even if you end up winning the case, you still have an obligation to obey the TRO for that reason - and you can (and should) be sanctioned if you violate the court's order.