I would dare say that large swathes of all sectors of society have unconscious bias; not just white people. To suggest otherwise is arguably worse, basically expressing a conscious bias against white people.
Depending on upbringing and life experience, for many people they will have unconscious bias, whether that be against Tories, police, posh people, rich people, privately educated privileged people, estate agents, religious people etc. take your choice of antipathy.
Am I wrong? Can anybody say in all honesty that they don't somewhere hold negative stereotypes against some group or other. I know I would be a hypocrite if I said I didn't.
Is it more acceptable to have unconscious bias against some groups than others? I don't think so if that negativity is wilfully acted upon; it's equally as bad.
To have unconscious bias is to be human. To act maliciously, to deliberately treat somebody different based upon that is wrong and unacceptable. If the people who encountered the barrister did so then they should be ashamed. If they acted unconsciously then they were probably embarrassed when they found out the truth and should not be vilified.
It's probably not helpful to just keep highlighting it as a one way street that only affects one group as that can potentially reach a point where it breeds resentment or loses support for what really ought to be the bigger picture:
It's human nature that people may hold biased views, it's unacceptable to purposely act on those. Treat everyone fairly and equally when you encounter them.