It's JUST a song, not really sacred.  There are many other patriotic songs, some of which have even been subbed for the 'Star Spangled Banner'.  Trump is treating the whole thing as something which disrespects the 'sacred' flag, to try and show how much he 'loves' America, when he only loves himself.  As usual, it is all about Trump and his white supremacy belief.  It shouldn't be.