Cross-posting can mean posting the same content on two platforms, not linking to content on another platform. Linking to Facebook would likely still earn him a ban.
Yes - that’s what I interpreted it as. From the policy, Cross-posting covers when you “…post content to Twitter from these platforms…” (emphasis mine).
Of course, I suspect the reality is that even people at Twitter don’t know if this falls under the policy or not.
I’m not sure why people here keep talking about the post being ‘newsworthy’ - that is not mentioned in the policy at all.
The sheer quantity of posts on Twitter suggests to me that they will need to automatically ban folks for linking to some external sites. So I guess the question is would Twitter unban Carmack if they performed a manual review later?