Totally loved this chapter... even though i HAD to read again the chapters from the assault to the king's palace in order to remember what had happened before this last hiatus and understand what was going on now!
Before and during his fight with Neteru, the King (thanks to Komugi) was getting more and more similar to a human, forgetting his ant nature. This was an inescapable step of chimera ants' evolution, a necessary choice between humanity and their ant/beast identity.
When his memory was erased by the explosion, the King had forgotten the way he had chosen, and was starting to behave again in a beast-like manner.
Poufu had always wanted the King to be inhuman and against humans, and thus decided to prevent him from remembering of his previous choice, even at the cost of his own very life. How? Preventing him from remembering about Komugi, the very first human being that taught him that even though weak, human beings can be important. About Komugi, the woman the King loved. (even though it was explicitly said only in this last chapter)
That's why Poufu rushed back in order to kill Komugi and obliterate the thinnest trace of her existence and, when he realized he wasn't making it, he proposed this challenge to the King, in order to slow him down at finding evidence about Poufu's secret, Komugi.
This way, Poufu had almost succeeded at having Werefin killed by the King before he could talk about Komougi : Poufu said that Werefin could not answer the King's question because otherwise he would have revealed the secret, thus invalidating their challenge.
Was it luck or not, Werefin's supposed-to-be last word was chosen wisely: her name was enough to awaken Meruem's love towards her, and to remind the king of his ultimate choise: being no more ant, but a human being, respectful to life and weakness.
Poufu's life, which he was ready to sacrifice, was saved, but his wish was crushed.
Now he will probably try to get his love back, and then die because of the rose's curse. Though he now is one of the good. A tremendously strong one of the good. =)
I didn't dislike this last arc at all, leaving arts and hiatus aside.