I’d love to see the language in the HOA that prohibits this display. Even if there is some silly language, the fact that the HOA have been silent about it for a year presents some legal issues for the HOA.
The article says that “the authorities”. An HOA is no authority, they have a set of codicils to which all home owners agree to follow.
The banner was designed by the U.S. Government in World War I specifically for display in the home of a family with some family member serving. One Blue Star is displayed for each serving family member. When one of those family members fall in action, a gold star is affixed over the Blue Star. It is not a flag, again the specific language of the HOA would have to restrict a window decoration. Is a paper pumpkin allow in a window? If so, this lady can tell the HOA to stuff it.