How can you ban a newspaper from the ground? Assuming football clubs don't sell newspapers inside their grounds does this mean anyone with a rolled up copy in their jacket or bag has it confiscated or is refused admission?
I think the tide has already turned against The Sun and will continue to do so. Their absurd anti-Labour propaganda during the recent election campaign doesn't fool people like it used to, but whilst I won't buy it or read it myself, and encourage others to do the same, I think that's a bit over the top and probably more likely to cause a siege mentality among its readers and make them all the more determined to support it. It would be the thin end of the wedge IMO; other clubs could start banning all sorts of arbitary items according to personal political or social views.
(Banning links from an independent forum is another matter and the prerogative of those who devote their time and energy to sustaining the forum for the benefit of other users.)