@KeetThanks for the reply. Love it when people help me think!
The single purpose of punctuation is to make text readable as intended by the writer.
Umm... Really? Are you sure? I'm not picking a fight here; I'm really asking. Here's why I'm asking. First, there's no citation for that statement. (Not a problem! No need to back everything up with citations -- this is a forum!) But, without a citation, I'm taking this as your shorthand for punctuation, and I agree with it in some ways, but I think it needs a little context.
Specifically, there is nothing inherently helpful about punctuation. It's artificial. People have to learn to interpret it, and they learn in the context of those standards. So, if an author doesn't follow a standard, it jumps out to those who are familiar with it and can throw them out of a story or raise questions about the author's skill. (The latter is probably more important for professional, non-fiction works. Most of us have read stories where we overlooked a lot of grammar or spelling or word choice errors because, "Damn! That's a great story!")
A little advise when offering URLs: check the date of the article, your link is pretty old (2014).
Thanks for the advice, but, yeah, I know. "Pretty old" is relative. For some scientific fields such as psychology or climate science, a seven-year-old cite would provoke me to go look for current research. And, even then, it would be topic specific. For rules of the English language, not so much. And, as I said and the article I cited made clear, the rules seem to be in flux. I still came away with the judgment that both quotes in the OP were correctly punctuated for American English, and I've yet to see a "standard" that says they are incorrect. In any event, by the shorthand of do they work for the reader, I think they would for the overwhelming majority of those accustomed to reading American English.
I read both your citations. The APA Style is for psychology, and widely used in other scientific fields, but does not seem to be a common standard for fiction. The author in your second cite Uses the Chicago Manual of Style. She specifically notes that CMOS does not recommend the use of single quotes for words not being used for their meaning. That construction in her post is awkward, but I read it to mean that one should stick with double quotes, which was what the post I cited suggested.
Finally, why should I worry about whether a url I use as a link is .amp? I had never heard this, did a quick search, and didn't find anything that suggested using .amp would cause problems for forum users who wanted to follow a link. It appeared the impact is on mobile devices, and the link I used works fine on my phone in Opera. So, maybe there are things I don't know? Happy to be educated on this, but right now I can't find a reason why a link to a .amp page would cause problems for forum users.