I will admit I've thought about this topic in a manner similar to the OP. There was a part of me that felt like the comic presented an unfair dilemma, since, as a gamer and a fan of fantasy, I've enjoyed stories where the evil races got what was coming to them. Now, I was never the type of gamer who, as a player, murdered green people just for being green, and certainly not while playing a good-aligned character. Still, most often in those stories, the goblins or the orcs or whoever are the ones who started it, and once the fighting got going, I was as likely as anyone else to take them down and not think much about doing so. So then, was the comic a shot at me? I had to ask that, and if it was, if I deserved it. I don't know. I'm not the type of gamer who comes for the bloodlust, though I will admit to enjoying combat and sometimes facing enemies that are unambiguously bad.

In the end, I don't really think Mr. Burlew's message is, "If you've ever killed a goblin in an RPG, you are a terrible person and you should feel bad." After all, he went out of his way in Start of Darkness to show that Redcloak, while he had suffered some level of injustice, as had his people, the man himself was no mere tragic victim. Redcloak has all sorts of agency, and after the first incident (where he was a victim indeed), he has been pretty heavily responsible for his own woes and those of his people. Also, his hobgoblin horde has mostly proven to be pretty ruthless and brutal in their oppressive occupation of Azure City. But these are individuals and societies, born of actions and choices rather than birth. They're evil because of things they've done, not how they were born. Also, while we have been shown that many amongst the Sapphire Guard were overzealous and have done very bad things, we have also seen plenty of paladins who are kind and decent people, like O-Chul, Hinjo, Lien, and Thanh. These are people who proved themselves good through their own actions and choices rather than simply because it's a class requirement. Also, as adventurers go, Roy, who is the nominal hero of the story, has proudly proclaimed that while he may kill foes if necessary to protect himself or others, he would never murder a sentient being because it was easier than talking to them.

All of this tells us a great deal about how Mr. Burlew views morality. Good and evil do exist, and they aren't just arbitrary team names. Alignment is decided by one's actions, not innately by one's race or class. There are no easy outs or shortcuts to right and wrong, only choices and actions.

I suppose what I'm saying is that the comic is not a guilt trip for gamers, or perhaps it could be for some, but a reminder that these words, the alignment system in general, mean something, and can teach us something about ourselves, rather than just being an excuse to butt heads and roll damage.