FYI I've confirmed that this is real and not a Twitter hack via a mutual friend.
— Peter Todd (@peterktodd) January 1, 2023
IIUC he used Gentoo as his desktop and didn't keep different activities separated. So backdoored software is one of many ways this could happen; he may not have been targeted.
Use @QubesOS people. https://t.co/51PuGbJabX