Having no empathy for what Thjazi did to Bolaire is so strange to me because we have no idea what Thjazi did to Bolaire. That part of the story has yet to be told. Usually you want to know the context and the details of something before you make a determination about how you feel about it, yes?
"He kills people!" Yes, and so do all the other people in this campaign. There are very few saints in an adventuring party.
"But this is different!" Yes, it is. Because Bolaire was a tool given sentience by people who never gave any thought to what would happen to him or his siblings once they served their purpose. Maybe they were all supposed to be destroyed in the same play that destroyed the halfling shaper? Maybe the people doing the crafting were so desperate that they had neither time nor energy to give a thought to what happened after the death of a god? Maybe they couldn't spend any time considering or discussing it for fear of being discovered? We don't know and we may never know for certain, but that lack of consideration definitely impacts who and what Bolaire is now.
How does a disposable sentient object learn morals? Most creatures are taught that sort of thing in their childhood by their parents. Bolaire and his siblings had no parents and never had a childhood. They knew each other for a day before the play. What they knew of each other, the world, and their personalities was "programmed" into them for one purpose: to get a job done. For decades after that, Bolaire had no sense of self, he was simply a tool of war. He was used by mortals when they needed to destroy and kill, and put away whenever he wasn't needed for those roles. When he began achieving sentience, who were his first teachers about how to treat other beings? The very people who were using him to kill and destroy. Is it really shocking that he treats (some) people as disposable? As means to an end? The traveling play may have given him goals to strive for, but the people who wielded him for decades gave him the roadmap for how to achieve those goals.
How do we gauge how old Bolaire is? Do we date it by his creation or by when he gained sentience? How do you gauge a sentient object's intellectual or emotional age, their level of culpability for their actions? They have no life cycle, no developmental period. Is Bolaire an adult or a child, or do those designations even matter for an entity that never ages? For example, Azune probably killed people as a child soldier but do we give him as a child the same level of culpability for those actions that we expect of him as an adult? Both legally and ethically the answer is usually no.
If Bolaire isn't a person, how can he be culpable for his actions? We don't sentence cars to jail for hitting pedestrians. But unlike cars (as far as we know), Bolaire has thoughts and feelings, so he must be a person. So then why did/do so many people treat him as if he isn't? What is their role in making him what he is now vs his own responsibility for how he shaped himself once he found out he could?
These are delicious, complicated questions, most of which I have no answers for yet because we're still very early in Bolaire's story. Personally, all of these questions are far more interesting to me than deciding whether Bolaire is a good person or a bad person, because to be honest I don't think even Bolaire or Taliesin know that yet. I get people not liking Bolaire, like so many of Taliesin's characters he's abrasive, bitchy, judgemental, cruel, and generally difficult. For some people that's a feature, for others a bug and that's fine. What I don't get is being unwilling to engage with these interesting themes for...what end? To be morally right on the internet? These aren't real people, you're not going to publicly shame Bolaire into being a better person by putting him in the fandom version of stocks in the public square. So why not let the story tell itself before you decide how you feel about it and him?