See my above post, and tell me how you would respond differently to the
"straightforward replies".

Seriously, just write down the first things that pop into your head,
and tell me how they are different from the original poster's replies.

I'll meet you halfway. If the explanation is good, I promise I will
start over and completely reconsider the asshole factor of the original
post - if you promise to write down how you would honestly feel.

As for my second question -

Maybe I'm being naive, but isn't the fence his property? Wouldn't the
attachment of another fence to pre-existing posts constitute "use" by
someone else?

And again, I am all ears - without bias. Let's work on these two
questions by themselves.