Hmm. I have the latest version of the H8S/2xxx manual and it says something slightly different, although in practice it's probably equivalent:

Code
The instructions that disable interrupts are LDC, ANDC, ORC, and XORC. After any of these
instructions are executed, all interrupts including NMI are disabled and the next instruction is
always executed.

Is there an actual test case for this yet with cybikoxt or more of a "we know we're going to need this"?