Technically, he broke the law by vandalising the property. I think his better move was to tell the business owner the proper flag etiquette (I don't believe the law requiring the US flag to be higher than another is constitutional given recent precedents on free speech). It appears the business owner meant no offence and was unaware of the 'rule' on how to fly flags. If I were to see that at a business, I would tell the owner about it. If I learnt it was intended as some sort of a slap in the face to the country, then I would likely choose to shop somewhere else.