Actually, it is not hatred that causes these people to object to the Australian flag. It is "the rules".
In America there is a terrible ruling body called "The Homeowners Association" (herewith known as Association Nazis, or AN for short).
When you move into a community under the control of the AN's you give up all freedom of choice on what you do to the outside of your property. Their rules are "for everybody", and "for the good of the community". Most often the AN's are retired busybodies who have nothing better to do than to look for infractions of their "rules". Apparently this flag was a violation of the "rules" that these fine people agreed to abide by when they moved into the "community". I can guarantee you that the flag is just the tip of a large and terrible iceberg. You can't leave cars parked over a certain amount of time, can't repaint your house unless you use approved colors, can't do an addition to the house without approval, and just about anything else you can think of. I assume that in Florida, pink flamingos wuld be OK as a decoration, but perhaps not. I know for a fact there is an Association in Idaho that does not think pink flamigos are an appropriate outdoor decoration in your yard. Just ask my best friends that live there. Now we go out of our way to plant flamingos in the yards of the AN's. (We have quite a few left over from a party!!)
So, as you can see, it is not a purposful snub. If the flag was Irish, British, Italian, or from Djibouti, the results would be the same. The AN's have a very narrow and one track mind.
Why anyone would voluntarily give up the freedoms they do to live in a "community" under the rule of AN's is beyond me. Perhaps they just like being told what to do, and when to do it.
So, although it is hard not to take it personally, I hope this helps explain a little bit. I have become somewhat used to the American flag being disrespected throughout the world, even here in the US.