It looks to me that so far the issue is limited to systems with an HMC.
That is wrong. So wrong.
Firmware is on all Power equipment. At least Power 5 and above.
Irregardless of whether or not you have a HMC.
HMC code is only on HMC's so, only in that case are you correct. You're
right, if you don't have an HMC then you won't have an issue with your HMC
code. And if you dispose of all computers, phones, TV's, etc, you'll
really reduce your risk.
IBM i itself can be affected.