This is one of the issues I find with moral subjectivism, or more rightly, people whom claim to be moral subjectivists.
Moral subjectivism is the theory that morality is wholly subjective, there is no real truth-value, just opinions of what is moral. This means that if a person, or culture, thought it was moral to torture babies, it would be moral to do so.
Let’s give a real-world example of this, some cultures think it is moral to kill homosexuals and atheists, yet subjectivists say they are behaving immorally. They are saying there is a value above that culture’s opinion. They are treating morality objectively rather than saying “well yes, it is moral in that culture” or “it is not in accord with my standard but it is with theirs”.
If morality is wholly subjective, then right or wrong should not be words uttered in regards to moral judgements. The second you do, you are in conflict with your belief that morality is subjective.
Perhaps, being charitable, it is an err in language. When they judge another, perhaps they are speaking of “not in accordance with my personal standard”. Again, we are back to an issue with sloppy language and the need for clear and concise language. The terms right, wrong, true, false have no place in a subjective system.
I wonder if part of the problem is a lot of the subjectivists come from the online atheist community, many whom haven’t looked into morality all that much. The community is rife with scientism, and there are lots of FACTS about the world. They are used to dealing with facts and the theories that describe them. A fact, by its very definition, is true. There are things perceived as facts, of course, or things we realise were never actually facts, but a fact is true.
So when you’re used to dealing with things that are objective, it can be difficult to change your mind to subjective things. Perhaps it is the way we are used to dealing with things too.