It is something I have talked about like a thousand years ago, but while it's subtle, Spoke's perception of who is Okay to kill changed so much, his mindset about killing and griefing and everything changed. When he was trying to prove he is a good person, during and post-exploit arc, he was against both of those things, heavily.
THEN it evolved into wanting to kill Only Ash. THEN it evolved into killing Only the diamond players. He felt horrible for killing Rose, because she could speak, and was a person in His eyes. She was afraid, and she had a name, and she was visible to the eye.
THEN after he killed her, it evolved into not caring about any invisible player, they were nothing but soldiers that aided Ash and thus were not human to him. And THEN his army was completely visible (Spoke Galactic Empire), they had names, but couldn't talk, and he slaughters them mercilessly. THEN self defence and mindless killing blended together, finding more and more enjoyment in having the upperhand.
I think really is what motives him so much in hindsight, is having the feeling that he is in charge in any situation, that he does whatever he does because he wants to, not because he's ordered to. Yet he falls so quickly into the role of a follower, the moment someone shows him even a silver of affection. Parrot, for example. Spoke assembled the army to fight for the crown pretty much on his own, and fully was under Parrot's command, even after Parrot invited him to speak to the army because the army was his to begin with. Does that make sense.
It's actually really easy to get into Spoke's good graces, all it takes is for them to be just a teeny tiny bit nice, and don't treat him like an irredeemable monster who is beyond saving (something that he has Heavily internalized, and leans into. Because it's easier to be the bad person they say you are, than to prove them otherwise. He has tried so many times to prove he's good, but it always just fails. Yet. Yet, despite these failures, he can't help but jump at every single opportunity that might paint him as heroic. Opportunities that he always ruins in end), that's what drove him so close to Ash too.
Ash showered him with praises, saw him as something useful, as competent. It ticked off both of Spoke's desires, because he needed to be close to Ash to take him down, and believed he was a good person was Infiltrating, and his want be treated as a human being. Well, until of course, the infamous Ash monolouge about Fish Bucket being rotten to his core, that he is worse than anyone Ash has ever seen, that dripstone is his sharp blade. (A weapon, that he utilised in his trapping days during the BAT arc. Everytime he used dripstone to kill a target, my heart dropped. And he used it quite a lot.)
It makes sense why the fanbase Ignores all of Spoke's character development, because they either completely skipped s1 and early s2, or they view everything before the episode Mapicc disappeared in as unnecessary. Because they reduce it to just silly, unserious filler episodes. (Which they aren't. But I won't get too deep into it now. 100 days arc my goat......)
Uu characters though, it is so tragic. Because they never saw, and will never get to see how much he tries. There are like maybe 10 whole episodes, outside of his own pov, where he is there. He is completely isolated from the rest of the protags, and their perception of him is so skewed and wrong. This doesn't just apply to protags though, this applies to Leo, this applies to even Jamato who supposedly spent his time watching Spoke's every move, this goes for so many people.
He was so afraid of being like Ash, so afraid. He tries to cancel out every bad with something good, but it's never enough, and it will never be enough. To do something good, he must kill and kill and kill, and hurt others in ways that only make sense to him. And it stings so deeply, that everyone always undermines how badly people hurt him too. Like we've never seen anyone acknowledge how Ash hurt him, how Jamato hurt him, just how much they had put him through, pitted him against his only friends (the only people who are willing to look past his rough exterior. They're too close, is the issue, and he tries to hold onto them by any means neccesary. Anything will suffice, as long as he's not alone).
He doesn't kill Ash because he's a better person. He doesn't kill Jamato because he's a better person. He kills Leo, had gotten enough dirt on his name to make him seem better than him no matter what he does to take him down.