It still strikes me as a song that you could read either way. Even if it was written by someone (Toby Keith?) who thinks lynching is OK, once written a song can take on a life of its own. The views of the author ultimately don't matter that much.

Reading it here it seems to me that it is drawing a parallel between some current types of law enforcement and lynching. So if you start with the assumption that that kind of law enforcement is the right kind, the logic is that that goes for lynch-law as well. Or you can go the other way - start from the assumption that lynch law is wrong, and carry that over to equivalent types of law enforcement.

It has occurred to me, and I've mentioned it in another thread, that there is a real parallel between the Iraq War and a lynching, and Toby Keith seems to see that parallel as well (while welcoming it, so it appears.)