Although I’m not thrilled about it, flag etiquette has become irreversibly more relaxed in recent decades. I’m aware of the “old” rules because I was a Boy Scout and raised on Army posts, but a lot people my age (33) and younger (and even some older) just were never taught proper flag etiquette. Nowadays, you just have to judge people’s intentions with the flag, rather than their actions. I’m sure the PGA meant no disrespect.
I know the flag rule is unenforceable. A long time ago the Supremes ruled that burning the flag and wearing it as clothes falls within the 1st Amendment.
Sometimes my shorts get into a twist. If you are going to use the US Flag a a prop, ( like this golf tournament ) at least get it right.