Yes, I originally thought of it as the most plausible explanation. But then, Harry's remark must also make Draco's Patronus ineffective, just as explanation of Patronus 2.0 would, which very likely isn't the case.
It might yet make it ineffective, but only if Draco grasps the implications. Harry might begin the next chapter by deciding to shut up and not explain to Draco why it matters to him that snakes have a language. (It obviously doesn't matter to Draco, who I don't think has fully accepted that Muggles are sapient, despite their obvious language.)
Update: This post has also been superseded - new comments belong in the latest thread.
The second thread has now also exceeded 500 comments, so after 42 chapters of MoR it's time for a new thread.
From the first thread: