I would be horrified to actually fireball a group of people, even if they meant me harm. But that's not actually happening. There are a lot of things that we ignore to play, because the real world is rough enough.
There are a lot of veterans who would, in the moment, not hesitate to use a fireball in defense of self, family, and unit... might bug them days to decades later, but not at the moment.
The military trains killers. It takes normal folk, most of whom are reticent to kill, and overrides that key "Thou shalt not murder" commandment - sometimes by logic & justification, sometimes by rote training.
Prior to the 16th C, the military was largely a caste - the gentry - with its knights and minor lords, and their trained men at arms as a second, larger, caste. But they trained from youth to be ready to kill fellow men. And lived in a society where the meat on the table was living the day before, sometimes even a near-pet. Everyone knew that lives depended upon the deaths of lesser beings, so the justification of the neighboring ethnic group as lesser beings put their lives right down there with sheep, cattle, dogs, and wolves, by behavior.
I don't think there is a single, right way for everyone to respond. We don't have to agree or have the same response. If one person who loves Tekumel will now boycott it, that's fine. If another still loves their Tekumel books, that's fine too. And we should be tolerant, imo, of this fact: that different people will respond differently, and not being offended in the same way we are, or being offended when we're not, isn't necessarily a moral failing or something that threatens us.
And yet, many have taken positions that to not condemn the whole corpus is to approve the whole corpus and beliefs of the man behind it.
I've seen enough to think it more likely than not that Barker was at some level a neofascist. But I'll still note that the racism common to it didn't surface in his professional life (it would have been news), and didn't appear to factor in to his dealing with fans, so I still question the level of commitment to it Barker may have had.
The political discussion is actually more interesting and enlightening than the original topic, too bad it's in prohibited turf.
I will say that there's not yet been an LG society detailed in a product I've read that isn't a dystopia to me. Most of the societies described in fantasy games are dystopian; if they weren't, there would be no adventure there...