A segment of white country fans don't like the song, not necessarily due to the lyrics and its imagery but, mainly because they see right through Aldean being a fraud posturing to be a small-town vigilante cowboy...if the song was written by somebody born and raised in a small town those fans would react differently.
Country fans are somewhat like Hip-Hop/Rap fans in the sense that authenticness matters, just like how people always talk in disdain about rappers who're from the suburbs putting on a show acting like they're super hood/thugged out individuals but it's the complete opposite....well in regards to country fans replace the word hood with a small town and replace the suburbs as big city.
The ones buying, bragging, and boasting his song up are likely the racists and pro-police/blue lives matter type crowd looking to piss people off.