yeah, i think that is just the way it is with the file system when space gets short. however, one thing you can do is the pivot-overlay procedure,
https://docs.onion.io/omega2-docs/boot-from-external-storage.html

@Douglas-Kryder @ccs-hello One more point. I've not yet metered the O2+ in the troubled dock configuration. Have only "known" lack of power up by lack of LED, basically not knowing all of the facts. Just got out a USB-LVTTL converter. Will connect later today to tty0 in breadboard dock to see if I can reflash. If so, the O2+ device may emerge from some hosed up state that prevents full boot, or perhaps even continuation past very early boot, to come up in a healthy state that will work in all configs.

--Bill

Thanks for the explanation @luz, I could not remount the file system with rw. I did a factory reset and now it is writable. I was able to mount my usb card into the omega 2 and I expanded /overlay