referring to Epicurean philosophy as EP is off-putting. It's very in-group jargony with no semantic content to a wider world.
What's the natural audience for Epicureans? (I genuinely don't have an answer. Thoughts?)
I think these questions are related. I agree that the issue of the "ism" terminology is lost on most modern English speakers (hard for me to be sure about other languages) and I don't think the question should be made a priority in dealing with someone who doesn't see the point. I do think that some interesting points can be made by discussion the question of "isms," because there are lots of aspects of Epicurean philosophy beyond just the role of pleasure and pain, which is why a label such as "Pleasurism" or even"Hedonism" doesn't work for me, and why I never use the "Hedonist" label. Discussing the issue of what "Epicureanism" is helps flesh out that it's more than just a system of ethics. But the way most people understand the "ism" suffix (in my experience) is that it just means "system of thought" and there's nothing necessarily negative about that.
The natural audience probably would be a subset of whatever type person it is who wants a coherent system of thought - not everyone seems to want or care about having one. I don't know that this should always be true, but it seems to be a lot easier to identify the type of person who is naturally "not an Epicurean" than "naturally is an Epicurean." There's definitely a list of attributes that can be identified, though, and among them would be the degree to which a person values thinking independently from the larger group. The issue isn't a matter of objecting for the sake of objecting, or naturally being uncooperative, but more a matter of determination to follow one's own sense of pleasure and pain rather than taking those cues from the larger society.