Enevhar Aldarion
Hero
The rule states:
Your rage lasts for 1 minute. Lt ends early if you are knocked unconscious or if your turn ends and you haven't attacked a hostile creature since your last turn or taken damage since then. You can also end your rage on your turn as a bonus action.
It's easy to add:
"You rage also doesn't end if you are under sufficient stress that is equivalent to taking damage or your life is in imminent danger."
That's not a change, that's an addition. Which fits with 5e's exception based design.
If formally written like that, it is more a "house rule" than a "ruling". But terms of additive house rules, that's minor. I run my 5e game with several much more dramatic and impactful house rules.
If the player just chooses the rage in a non-combat situation and asks the DM if it will last, and the DM allows it, then that's a ruling, because it lasts for that single instance.
Eh, as mentioned earlier in this thread, I feel the rage is only available if the character is in an initiative situation. But, if I were being lenient, I would change the first line of the official rules to include "hostile environment", since it seems a lot of DMs use initiative in those situations, like the one in the OP. So that raging river that is hostile to you could trigger it or that stubborn door that your normal strength just can't seek to break could trigger it or that obnoxious bard up on the stage using you as the butt of his jokes for an entire show could trigger it.