I must have accidentally typed j instead of z. It’s bz2 format. Rename to .tar.bz2 or just do tar -jxvf
The package doesn’t open, it says “not in gzip format”.
Source: Published by Martti Malmi on GitHub in February 2024 as part of his testimony in the COPA v. Wright trial. The full correspondence archive is available at mmalmi.github.io/satoshi/.