So I woud say, regardless of the circumstances, any time a unit with unsupplied marker is destroyed, it goes to the Surrendered Units
Box and counts as a VP.
Destroyed in COMBAT
is the key term here..
There is an exception and that is overstacking.
Rule 8.4.3 states:
[8.4.3] Overstacking Penalty: At the end of any Phase or
Battle, the owning player must put any excess units of his
choice from that hex into the Shattered Units Box until it
conforms to the stacking limit (8.4.1), Unsupplied units are
put in the Destroyed Units Box.
This allows a convenient escape method for players to juggle units around and then 'destroy' the unsupplied but overstacked unit denying the enemy a VP.