25Avalon: As I wrote earlier, I think the way to influence social media is for people, organisations etc. to stop using the channels that allow abuse. It is simple and probably more effective than other options, at least in the short term, but a solution that, sadly, most will not accept.
As it happens, I would not take the knee either. I think there are better ways to make a gesture of togetherness. I would not support 'Black Lives Matter' either; but I would (and indeed have) supported 'Kick It Out'. To me, it makes sense to unify all of us against racism rather than define which gestures we must adopt. When Michael Holding says on the Sky Sports advert, 'we're all in', it is inclusive, not exclusive, and can appeal to all. It certainly appeals more to me.