The Western Mail's chief reporter has been asked to step down as a Wales Book of the Year judge over his comments about the Black Lives Matter protests.
Literature Wales said Martin Shipton's "aggressive language" was "detrimental" to the organisation's values.
Among dozens of tweets sent in response to several people, Mr Shipton asked why the demonstrations were being allowed to take place during lockdown.
He said he was not asked to explain his comments.
"After expressing my concerns about the Black Lives Matter protest in Cardiff, which undoubtedly broke the Welsh Government's prohibition on public gatherings of more than two people, I was subjected on Twitter to a vicious tirade of abuse and bullying that lasted for days," he said.
"Many of the tweets questioned my right to express an opinion, called into question my credentials as a journalist and attacked me on the basis of my age.
"One of my guiding principles is not to appease bullies, so I defended myself by responding robustly to my attackers."
The disease, he said, had taken "many more lives than the Minneapolis police."
"I just don't see what value there is in holding a demo in front of Cardiff Castle about the murder of a black man in Minneapolis," he tweeted.
"It's politically naive and virtue signalling".
Mr Shipton insisted in the tweets he was not condoning police brutality, but had "been demonstrating my membership of the awkward squad by taking on some woke, group-think dogmatists".
Literature Wales said it "would like to thank him for his work".
This year's shortlisted contenders for the competition will be announced on 1 July.