So, my understanding is that either an em dash or comma would be correct in these instances. I could be wrong. I voted for el dash because I feel like the way the author is abusing the semicolon indicates they're trying to create a break but then add on/move on. However, esp in the first, I see how you could argue a comma would be more, or at least as, appropriate. I've tended to be an em-dash happy writer in the past, myself, which would also explain why I chose that option.