It's normal that CPU1 is stopped in OF. OF uses only one CPU, but initializes both and send CPU1 to sleep. Has nothing to do with boot-args. CPU1 has to be "waked up" by custom-software (like a OS).
But If boot-args CPUS=1 it seems to be a bit different: Custom software won't see the second CPU - system appears as a "single chip" system - nothing to "wake up". If you have MacOS you should see that in CPU-Monitor. Nevertheless both CPUS are shown in OF.
I think, one CPU is now shut-down (hidden) by OF for custom-software, so that OS can only see one CPU and starts now properly....


Btw.: Better to be a "Schisser" than having a unusual system!