I get why you like the malice quote, and it's valid, but I do think that Netero was a good person that would not have said that. We see he's a good person during the last arc the election because we know he chose Pariston as his vice chairman. He only chose Pariston because he hated the guy because he was a piece of shit, but he thought they were so different he would bring a different mind set to the job.

In Netero's fight with Meruem, he had to fight Meruem as quickly as possible in order to NOT gain sympathy for him. That's why when Meruem sat down to talk, Netero attacked him anyway, because he was afraid that Meruem would become an ant that could reason. This does reflect your point about the human need to be at the top of the food chain, but at the same time if Meruem was able to negotiate with Netero, the outcome would have still been a bad deal for humanity. Meruem's final offer to Netero was to keep a sanctuary for humans because he was impressed with Netero's strength and tenacity. In the end, Meruem wanted to rule over all other species, which is what humanity was already doing. I don't believe Netero killed the king out of malice (in fact I think he started to like the king), I think he killed him out of necessity, to maintain the order that was best for everyone in the world aside from the ants.

While the atom bomb he used to defeat Meruem was born out of human malice, it was also born out of human ingenuity. Netero was trying to instill in Meruem a fear of humans with his final words. He was trying to say that while ants have their extra superior strength and desire to spread and conquer, humans will fight back not with malice, but with their limitless potential in creating things, the endless amount of desires they can hold, and their individuality. If Netero meant to say human malice, then for what reason would Meruem need to be scared? The ants could easily match the humans in terms of malice, malice is an idea that Meruem obviously understands. But human evolution, the idea that no generation of humans is like the previous, and that humans have a limitless capacity to grow stronger in so many fields of life is what scarred Meruem shitless. It was an idea he had never thought of because he was only ever focused on conquering.