We invent a new technology by which to transfer things, and suddenly the existing law doesn't apply? New technology is inherently lawless? Being "with computers" makes it different?

I don't think so. It's the same old stuff, merely with a technology upgrade. Be thankful, so the first amendment doesn't only protect quill pens and lead movable type.

The comments on foxnews.com are at the borderline, so it wouldn't be bad to flip a coin. A reasonable approach would be that deletion is restricted to crude insults and off-topic rants. It doesn't really matter though, because the foxnews.com comments sit on the border between being a publication and being a generic public communications medium. There is no point splitting hairs.