The choice of words is very important and not trivial in the least. Notice how you just said "piracy of a song", when in fact the copying of a song is not "piracy" which equates to robbery aka theft.

The words we choose are very important when discussing ideas, just ask the republicans who have used this technique for years to sway the public to their side on various social and political matters (death tx vs. estate tax being one example).

If the people who engage in it call it theft or piracy, because they think they are stealing, then it's morally equivalent.

I agree with you about choosing words carefully, but either choice doesn't change the article. In context, the semantics were irrelevant.

The people who engage in it don't call it theft or piracy. At least not any of the ones I know.