We currently cite ArxiV, we cite books out of print, we cite websites, heck we cite 'Mein Kampf' when discussing facism. We cite anything that was used as a source.
Banning citations means either changing the above practice, or banning certain sources from being used by academics. That is sacrificing science for the sake of ideology. We ought to consider sources for their inherent quality, not whether we like their publisher.