Thanks, gents.
I just discovered that United Airlines set their MAA after pushing TOGA (autopilot coupled approach), so the list is correct in most respects.
This either means that aircraft of this type are capable of making a go-around (during an autopilot coupled approach) without a MAA dialled in or United have modified their aircraft to allow it. UAL seem to have a lot of non-standard procedures, with aircraft to match.
Actually, I was trying to look more at the aircraft logic side of things, rather than procedures. However, I was slightly concerned that if the person dialling in the MAA had slippery fingers and let go of the knob at the wrong altitude during go around, the aircraft might prematurely level off. Or, if the MAA was relatively low and the go-around was performed at a relatively high height, then the pilots may fly through the MAA (because they didn't set the MAA fast enough).
Cheers.
NSEU