This honestly doesn't seem like a good faith counterargument.

Not that the lack of good faith diminishes the merits of an argument, why do you think so?

There's a big difference between doing something innocuous that upsets a person because of some hangup on their end, and unwillingly taking part in some activity that is genuinely hurtful to someone.

Ok so now you are making a distinction based on whether there is genuine hurt/pain on the victim. Are you now becoming the judge of whose pain is genuine or not? Whose to say the pain felt by Christians upon seeing gay people are not genuine?

If I'm grilling meat in my backyard, and the smoke wafts over and gives my neighbor an asthma attack, I sure as heck am going to apologize.

Let me remind you what we are arguing about here, which is your original statement of "If you unknowingly cause someone pain, the decent thing to do is to apologize.". Your statement doesnt qualify or require that the pain be at asthma level. So your example of changing a vegan's disgust to asthma is irrelevant. Again, who is to say that a vegan's disgust of smelling meat is not genuine pain?

The examples you're provided seriously aren't comparable here.

Are you able to articulate why? They are examples of people unknowingly giving others pain, which is precisely the topic of this argument. Just with the Christian example, what makes the pain suffered by Christians suddenly now excusable because it is based on a prejudice? Does that mean the definition of pain is going to be inconsistent / different depending on what your religion is?

The thing is I too would apologise in your asthma scenario. I also do apologise in scenarios where my actions somehow caused pain to someone whether it was my fault or not. Like you said, its a nice thing to do.

But what you are saying is that if I dont do these gratuitous things, then I become an asshole. And Im just cautioning you that going down that line could end up with some inconsistent outcomes.