I also stand corrected, actually! Poking around the MIPS site, I read this:

In addition to the shell and foam structure, helmets with a Mips® safety system have a sliding layer added to the helmet structure. This low-friction layer can be installed in the helmet at different distances from the head. Most helmets with a Mips® safety system have the sliding layer positioned closest to the head, allowing a sliding movement of 10-15mm on certain angled impacts, intended to help reduce rotational force to the head. Alternatively, some helmets have a Mips® safety system positioned within the EPS foam, between the foam and the outer shell, or even outside the shell.

So it is not absolutely or necessarily true that the MIPS layer contacts the head. I’d guess a bike helmet which uses a hardshell, not a microshell molded or bonded to the EPS as is typical, could have the EPS layer between those two elements. I haven’t seen a hardshell bicycle helmet in decades, but maybe they’re out there somewhere. More likely, I think that placement is used for other helmets in other sports, like horse riding, where hardshells are used.