If a limited amount averts a genuine threat to life, what follows from the concession?

Azimah and Rukhsah: Original Rulings, Excuses, and Two Forms of Concession

• Once necessity arises, any quantity becomes permanently lawful
• Use limited to the necessity, not unrestricted permission
• The usual rule does not return once the necessity ends
• One person’s excuse grants unrestricted permission to the whole community