Earlier quoted context omitted.
But there is no API here. The article makes it clear that you were intercepting client-server communication not meant to be used by third parties in order to write your own client. That it could be used as an API doesn't matter since the intent wasn't to create an API. I could do the same thing and write an app for, say, the tax agency by scraping its website but it would be a legal gray area.
There is clearly an API in play here. The article mentions it numerous times. The client app has to use an API to get its data, that's a downside of deploying a SPA. You need to make an API for it to get data from. If you don't want to make an API that exposes raw data just write a SSR app. If you want to deploy a SPA, well, you have to deploy an API as well and you need to plan around the fact that when you throw an…
Also it's easy to poke holes: does this mean that scraping data from html is always hacking, regardless of the expressed intent? (See recent Missouri case for what that might degenerate into.) What if it's "semantic web" and the html contains metadata specifically designed to aid data extraction?
I think the parents should own the data, and that's why it should be open. But I don't think drawing the line based on which kind of technology is used to deliver the content is a good method of adjudicating published intent.