I’m sorry, I thought you were talking about the entire sermon. A more careful consideration of the verses in question will yield a clear answer.
The confusion you’re facing is due to the fact that you’re misreading the JST footnotes. The three JST verses you quote are INSERTED into the text, making verses 25-27 in King James verses 28-30 in JST. The verses in question were NOT changed; they were shifted.
The three verses that were inserted were specifically directed at the Twelve Apostles’ missionary charge in the Old World; it is possible that they simple weren’t written in the New World, or that Christ did not include them in the sermon as they were not applicable to the audience in the Book of Mormon.
This small incident, sadly, tends to expose your methodology; you found a little thing that you thought supported your viewpoint, so you latched onto it without considering the wider view. It’s a common human flaw to tend to ignore things that disagree with our worldview; heaven knows, I’m guilty of the same weakness. It makes me wonder, though, how many other “proofs” you have against us that are similarly specious.