Not only that, but if it were the actual file on your local drive and not a link, there wouldn't be an option to "make this file available offline". There were cues which the author missed, but they were obviously not prominent enough which is a (the) design flaw.
Let this be a lesson that you should have multiple backups for anything important. I personally have 2 online backup systems and 3 local ones, the worth of which practice I learned the hard way like this author.
Also think twice before you empty the trash - you're manually making these files unrecoverable from the internet, and if your machine went up in smoke after you hit the button, you'd be screwed. That alone warrants serious consideration.
Glad you read the article though, now you're not going to fall for this flaw in the future.
For a techie, perhaps. For a non-techie, that's something they're unlikely to have ever seen happen in their filesystem. Even if they opened it in Notepad, they'd probably not know the ramifications of what's shown there.