Ain't that some inane Twitterati bullshit. The author is trying so hard to be inclusive to black minorities, it's starting to feel racist.
Emphasis mine. I don't think he wants to help fight racial equality. He just want to fight for a subset of black Twitter nerds, and from his ivory tower he equates them with an entire ethnicity. Then wonders if Mastodon, lacking Quote Tweets is unethical because how can black people communicate then?!
Spoiler alert, the black racial struggle is bigger than Afro-American nerds identifying with an hashtag on Twitter, with a deep love for quoting tweets.
He wonders if migrating to Mastodon without crossposting might be unethical because it cuts people who are stuck on Twitter off from the group who has migrated. You have deliberately misinterpreted what he said. Consider why you might have done so and why you think he wants to "fight racial equality [sic]." You've been hoodwinked into fighting a culture war that only one side is fighting. The same duped culture warriors who have been fighting against teaching about American history from the perspective of native Americans and slaves and have been fighting against some "war on Christmas" for the last two decades.