If they have not committed a crime or aided in a crime, I personally don't have an issue with it as if they have not committed a terrorist act they are by definition not a terrorists. Lets move the hypothetical situation a little what if they are not a member but are sympathetic to the grievances that ISIS has (not all of them are unfounded)? Are they guilty of fire-able ill thought at that point? I don't argue that this guys ideas are savory nor those of ISIS my point is there is a lot of ideas that people from all walks of life find unsavory. I am sorry but I just fundamentally disagree with cancel culture, which to me this is a byproduct of. To me the harm is greater than the cure.