My concern is more on the side of releasing the air, instead of inflating the wing. I do carry an SMB but is to avoid getting run over at the surface if I lose the flag.
The pull mechanism could fail before splashing when I make sure there's no air in the wing, or at the end of the dive when I'm about to surface and also want to remove whatever little air I pumped earlier if needed.
If it happens before splashing, I'll check the inflator portion. If both things are messed up, we usually have a spare on board or worst case I take my husband's.
If the failure is at depth at the end of the dive, I'll use the rear dump.
One could "what if" further, but I generally don't because my current dives are ridiculously easy, always within NDL, rarely deeper than 100', with a 3 mil and a hood at the most.
Starting next week or maybe the other one up, it will be with just a rash-guard and a hood so the wing will be part of the gear but won't be used at all, unless I find some heavy treasure.