seL4 didn't exist, but the commercial variants of L4 did exist although they were meant for licensing to embedded companies so AFAIK you could neither download

seL4 didn't exist, but the commercial variants of L4 did exist although they were meant for licensing to embedded companies so AFAIK you could neither download nor buy on the open market. (As the L4s were probably better known around 2005 than they are now, it's possible Eliezer was referring to those specifically.)