DND_Reborn
The High Aldwin
Because there are several ways poison can be delivered besides direct touch?So like, the poison eats through leather? Fine if it does, but otherwise why make the save?
Perhaps touching the chest disturbed the poison and some parts were inhaled?
Or after touching the chest the PC accidentally touched part of their exposed skin?
Or any other explanation
Really? It is D&D? Oh, well then...This is D&D. Saves are specific. This isn't a generic "luck save", which would be absolutely 100% justifiable. Some games have them. D&D should probably have them, but it doesn't.

Seriously, much of saves are luck. A big factor of saves in D&D has always been luck. Being stung by a scorpion, for example, doesn't mean you "resist the poison" with your hardy Constitution when you make the save. It certainly can be that, of course, but a bigger factor is the luck of where the stinger hit exactly. Perhaps it was far enough away from major arteries, etc. that the poison was injected but failed to get into your blood steam. Perhaps when the scorpion hit it failed to inject enough venom, if any, to injure you?
Let's examine a sample saving throw: CON 14 and proficiency +3, for example, vs. DC 15.
How likely will you make the save? Your total bonus is +5, so 10 or higher or 55%. Of that 55%, the break down is 10% CON modifier, 15% is "skill, determination, etc." via proficiency, and the remaining 30% (more than twice either of the other factors) is just luck.
LUCK is a HUGE factor in saving throws. Otherwise, why roll the d20?

I think the above points refute this statement enough without further comment.With D&D this is going to be a CON save. But that means you got the poison into your bloodstream. And that makes no sense if you were wearing leather gloves or the like.