User unihederon found a bug in chat.
The word reply is present tense, not future tense.
I know some will say, "but this only works if you edit your message within 2 minutes of posting it, to reply to a message that has already posted within the 1 min 59 seconds of you posting the original message." So yes, technically it could be considered a reply then, since it's replying to a message not in the future but in the past. However, this then messes up the UI design of having older messages appear above/on top of newer messages.