Law is far from my strong point, but isn't there a difference here between social media (including this place) and traditional publishing?
If you delete something you're fine. Would a newspaper be similarly fine publishing something and then deleting or publishing a retraction? I thought with editorial responsibility they have a different responsibility to anything published?
Also you can ban anyone, delete anything. You could ban me for being annoying or having too many views you disagree with. Twitter can do the same. Though luckily none of you do. You could say that dogwhistles with nazi undertones aren't allowed, so could twitter.
I think where the big social media companies can be rightly criticised is with lacking consistency. They took down loads of ISIS stuff, rightly so, but dragged their heals on that at first and more domestic terrorism much longer (imo).
It's a difficult balance to find, perhaps an impossible one. I'm seeing progress with the recent developments at least.