Actually, if you really understand what is going on with this post it is about local control. The ALA have taken over control of most libraries and the local people are ignored and have no input in the whole process. No one has advocated a federal solution here, but this individual is looking for a local solution to the library Nazis.
I agree with your post #7:
Does the city/county have any authority over the library? How is the library board of directors chosen? You will have a better chance going after politicians than you will library board. So hit the politicians who have control over library funding and/or staffing.
I've also said that my experience with one popular brand of filtering software shows that it's not a perfect solution. It doesn't filter out everything objectionable, and it does block nice conservative sites such as FR.
When I was a child, and when my children were younger, there were "child" and "adult" library cards. Children weren't allowed to check out the same types of books as adults were.
In the long run, however, the public library is not a babysitting service. Parents shouldn't be leaving children there unattended. If you're worried about your kids accessing porn at the public library, don't let them go there without you, and keep an eye on them while they are there.