Do you recall the TV model? A risky work around would be to follow the "Keep Awake" cable box command with a TV OFF command. Obviously, this is risky because someone might be using the TV at that time.

Unrelated, I had a system where the shut down commands had to be in a certain order. If I shut down the TV first, something in the CEC chain might turn it ON again. I wanted to shut the TV down first in order to suppress extraneous "No signal" messages and have the video shut down immediately after the button press. Ultimately, I sent TV OFF twice -- once at the beginning of the power down sequence and again as the final step. I had to keep CEC enabled between the YAMAHA receiver and SAMSUNG TV because of the HDMI ARC.