There was a not below 50kts limit on the bar alt on the Mk31 AFCS (Mk3) but you used bar alt to 200', checked for desaturation and then engaged rad on a normal let down.
On the 3A with the SN500 had no limit and you could use rad alt on manoeuvre all the way down from 1000' and bar alt to the hover.
Not really relevant since we don't know what the SOP was for the accident crew.
I merely raised the possibility of an AP faff causing disorientation.