Manual selective door opening has long been rejected in Scotland. I don't know the actual reasons for this but it has been suggested elsewhere there were safety concerns when class 170 was introduced and SDO was rejected. If anyone knows more feel free to PM me.
I'm not talking about manual SDO or UDS (much as this is used quite happily on some LNR services, though may well not be any more if all of the platforms affected have been extended, I forget[1]). I'm talking about ASDO with the guard pressing the open button as, as someone has pointed out after me, happens on SWR already.
As far as I can see there is no specific safety benefit or disbenefit to who presses the open button in this context. The ASDO will ensure it is not unsafe to press it and ensure the correct number of doors open.
There are other advantages of driver release, such as time, but those are not relevant to ASDO in and of itself.
[1] It may be held in reserve for occasional use e.g. if a Euston train uses platform 6 at Bletchley, which is extremely unusual but has happened.