I think we have very different definitions of 'respectable'. Maybe it's an American thing where absolutist free speech is worshipped as part of the cult of civic religion, but where I live Holocaust denial[1] isn't considered respectable or acceptable.

If you mean it should be taken seriously because it is influential, then yes I suppose it's worth knowing what they are saying (today that's defending child sex trafficking apparently, but that's not new ground for libertarians). Freep, /pol/ and Stormfront are all influential these days, but that doesn't make them respectable either.

[1] https://pando.com/2014/07/24/as-reasons-editor-defends-its-r...