I think it's a combination of both: a) modern corporate culture trying to make employees take on the company they work for as part of their personal identity

I think it's a combination of both: a) modern corporate culture trying to make employees take on the company they work for as part of their personal identity b) young, liberal people working in PR departments who would be horrified if anyone personally called them racist / sexist / homophobic etc These people go to work, see some random account on twitter saying "<your company> is racist" and a) and b) combined makes this feel like a personal attack on them that they have to defend and social signal against. This is the most likely explanation I have come up with, because as you said, none of this really makes sense from a logical business perspective.