I assure you that I, as a retired regular (an "actual retiree"), get COLA raises based on rank
How long have you been retired? Things have changed.
Retired Reserve get ongoing increases on the base rate until age 60, and then get retired pay ("pension" colloquially) with adjustments on it, but NOT on the base rate. IOW, if you retire at $400/month you will get raises to say $405, $410. But retired reserve will get a base increase along with the active duty rate to $420, $440, THEN after age 60 will still get raises from there. There is a definite advantage to retired reserve, though I don't have the current numbers at home. (OT, if anyone does, I'd like to see them, though I can check next time I'm at the admin office.)
And as far as I'm aware, once you have finished your 8 year initial commitment, or full retirement, they have no more control over you. It would be unfair, not to mention I'm quite sure unconstitutional, to hold someone to regs longer after they volunteer for more service.
Retired pay has changed since 1985 from 50% highest to 50% highest 3 to 40% highest 3, but it certainly isn't "optional" on the government's end. It's contractual.
I'll check here, too, but to me, "retired entitled to pay" would mean military pay and not retired pay, and as there ARE two categories, that would be the reason to specify.
Obviously, if I have this all wrong, I do want to get my facts corrected.