I'm not a big Joshua fan, but I do think this is a bit of a storm in a teacup. Asking people to support black business seems fair enough and it's certainly not binary (supporting black businesses does not automatically mean 'don't support white businesses'. Bit like Black Lives matter doesn't mean that white ones don't)

I am a big Muhammad Ali fan, and he said much more racist things than that. I'm not clamouring for any statues of him to be torn down .... and I'm not clamouring for Anthony Joshua to be blackballed, if you pardon the pun.