why didn't he say the (half)truth? something like, yes I did it, i found ONE all-heal-elixir in a dungeon (maybe that red-gate would be believable - or was that later...) it would be believable, give that guy - and other people - hope, and if Jin-woo has ever to reveal his possessions of the other elixirs, he can simply say, I found another one
but all in all good decisions from my viewpoint
@courgette for our vicemaster, I would say if Jin-woo let him ride Kaiser (?), the wyvern, and has an eye on him, he should be kinda safe