In addition, DM crossed a line that they shouldn't have crossed by re-hosting the content. But conflating iframe embedding and content theft is a bad precedent.
This is an unhelpful comment to make. But if you're going to take that tack, one could plausibly make the same remark in response to your comment. Because farther down, the post talks about the other time the Daily Mail used one of his visualiations:
They didn't just screenshot the map. They didn't just embed the map itself. They iframed my entire site, which is why the FlowingData logo and header appear on their site.
So there were two instances. One in which they copied the code and removed the code snippet, and another in which they just iframe-ed the page. The charitable interpretation of the GP's comment is that they were referring to the latter.
"So how did Daily Mail embed the visualization without the word “poop” popping up on an empty page? They downloaded all the files from my server on to their own server and deleted the snippet that brought up a poop alert. That way they didn't have to deal with those pesky safeguards I setup.
In other words, The Daily Mail deliberately stole my work."