Pilot recovered while pulling 5G? I'd think they would have designed the GCAS to avoid a crash at all costs, regardless of the Gs required. Crashing is worse
It is designed that way. It realizes that by defining a roll to level and +5G climb as a successful recovery, and preventing the aircraft from being flown into a condition where a successful recovery is impossible.
So if you're flying right above terrain and you suddenly fly down, the airplane should accept your inputs and fly towards terrain until the moment recovery is impossible and will then engage.