https://twitter.com/ID_AA_Carmack/status/1603931899810004994...
This is a very, very, very bad policy and shows with absolute clarity that Twitter is far from a free speech platform. Which deeply saddens me. Imagine how absurd it would be for Reddit or Hacker News to have a policy like this. In fact, a similar policy on this site would get my account suspended for this very comment.
More info in these tweets:
https://twitter.com/TwitterSupport/status/160453126179152281...
Also, the policy is vague about whether merely linking to content on a competetive social network results in a ban, or whether the post has to "promote" another specific social network (whatever that means). They say "cross-posting" is allowed, but they don't provide a definition of "cross-posting". Whether the Carmack post would be allowed would hinge on that definition. Either way, it's a boneheaded policy.