Sorry for being pedantic but they are using an en dash (–) not an em dash (—) which is a little strange because the latter is usually the one meant for adding information in secondary sentences—like commas and and parentheses. In addition, in most styles, you're not supposed to add spaces around it.
So, I don't think the comment is AI-generated for this reason.
"The en-dash is also increasingly used to replace the long dash ('—', also called an em dash or em rule). When using it to replace a long dash, spaces are needed either side of it – like so." https://en.wikipedia.org/wiki/En_(typography)
You're right, oops. I agree with your reasoning (comment still gives off slop vibes but that's unprovable). But the parent has been flagged, so I'm not sure if that means admins/dang has agreed with me or if it was flagged for another reason.
So, I don't think the comment is AI-generated for this reason.