Hobbit on Quest
Here's the thing - the death's door rule isn't presented as optional in 1e, whereas it is in 2e. So this really isn't a case of cherry picking or including the optional rule in 1e but ditching it in 2e.First four pages...a LOT of picking and choosing here on rules...
(2e DMG, original printing, pg 75).
If you are including the optional rules of 1e, you should also use the optional rules of 2e. 2e also isn't a 0 HP point (at exactly 0 HP you are unconscious, lower than that...you be DEAD...though a DM can allow it as low as -3 I suppose), and a LOT more lenient and nicer overall.