It’s the high-3 from when you were a Chief.
I had some free time and you got me curious... Since High-3 doesn't even look at rank, I was trying to find the blurbage in the Code and couldn't find what you were saying regarding a non-Warrant reverting to Chief pay. I'm not saying it's not there, I just couldn't find it under 6323 or 6333. I did find this in 6323:
"(d) A warrant officer who retires under this
section may elect to be placed on the retired list
in the highest grade and with the highest retired
pay to which he is entitled under any provision
of this title. If the pay of that highest grade is
less than the pay of any warrant grade satisfac -
torily held by him on active duty, his retired
pay shall be based on the higher pay."
I know that's what you were saying, but it's another indication that High-3 is still what you get, regardless of grade or rank.
Obviously you've seen this discussed on the AF side, so I'm not saying it isn't a thing. Admittedly, my eyes glossed over after reading several pages of the U.S. Code. Regardless, it's an interesting discussion.