If you are hung up on me seemingly being hung up on the antagonistic angle, let me give you another example: "The earth is round!" The earth is round, but I did not intellectually challenge someone who thinks that the earth is flat by making that statement. Declaring a position is not the same as logically defending it.
You missed the entire context of my post, which was a response to someone who claimed that telling someone that they are a murderer for eating meat is an intellectually challenging statement. My response was that just stating that argument, without any sort of facts or reasoning to back it up, is a moral condemnation, not an intellectual challenge.
I already said that any statement can be intellectually challenging if it has sound logic. This means that my premise assumed that the person would provide said facts or reasoning after making their statement, and was not just making a single declaration and moving on. Meaning, I assumed that this person would both declare their position and subsequently defend it.
The point I was trying to make is that saying "X is immoral" can be an intellectually challenging action if you do it tactfully. If I start the discussion with, "Do you know that you're a disgusting person for doing X?" it is unlikely that any facts or reasoning I later provide – no matter how extensive – will be effective in convincing others. From that angle, you're correct; maybe highly-charged moral declarations aren't very effective at stimulating intellectual thought and discussion.
On the other hand, eating meat is something that is very common. Most people do not question the things they commonly do; they just believe it is normal to do so because they have always done it. By saying X is immoral, given that X is a very common act, you are engaging the person from a perspective that they may not have considered before. Even if you didn't provide any reasoning or facts whatsoever, which is unlikely, it has the potential to make them ponder on the subject. So, it
technically can be intellectually stimulating, if the receiver of the message can suppress their emotional response to the abrasiveness of your statement (as many do in debates, for example) and/or decide to ruminate on the validity of your claim afterwards, but that's not something you can really rely on.
I hope that makes sense, because it is very late, I may have not written my thoughts clearly.