This comment is misinformed. Unix has always been multi user, and has always (aside from earliest days before anyone heard of it) been able to compile itself. Minix does not stand for multi-user Unix.
The reference is presumably to Intel's use of Minix in its CPUs - see, e.g., https://www.zdnet.com/article/minix-intels-hidden-in-chip-op... - as an example of a place where a multi-user OS (that can compile itself...) might be used for what might seem like an embedded-type application.
