>> Not sure what this refers to.

> For example you can't even see 4chan's homepage.

That's likely the same thing, the 4chan admins asking IA to omit them.

> I was contesting the claim that archive.org wants to preserve material. It's hard to trust that an archive will preserve the page you archived if the owner can come along at any time and wipe it.

Being able to preserve material depends on their surviving.