This has been a huge win for Kimmel, and Free Speech. When he returned, he not only didn't apologize, he went HARD after Brendan Carr and Trump.
Clearly, what happened is that the public outcry against ABC was enormous, and ferocious. They are a broadcast TV network that has had an FCC license as long as there have been FCC licenses. They have a responsibility to uphold the First Amendment, and they folded so fast, and so easily, that those who made that decision should all be fired. And America let them know that in far, far bigger numbers than they expected.
The "talks" that they were having with Kimmel were almost certainly him telling them how this was going to go, because he held ALL the cards. He had the law, the Constitution, and ALL of America on his side. He even had MAGAs on his side. He was negotiating from a position of Ultimate Power. He was going to say whatever he wanted, and they weren't going to have any say in it.
This was a battle between MAGA and Free Speech, and Free Speech won big. It was also a battle between Trump and Kimmel, and Kimmel won big, although I prefer to think of it as TRUMP LOST BAD. He was gloating that he had destroyed Kimmel, and now Kimmel is not only back, he is stronger, and more popular than ever, for having won this battle. It will be far more difficult for Trump to fight this sort of battle again. Now that the other networks have seen it play out, they won't succumb to pressure and threats so easily.