Alzrius
The EN World kitten
Again, the presumption here is that this is all an after-the-fact method of fleshing out a roll that's already been made. The DM isn't just reaching down to pluck the player's character away from them; the PC has already elected to examine the chest (with the understanding that doing so involves tactile manipulation) with the acknowledgment that a roll is called for (as well as the further understanding that a low roll can carry negative consequences). In this case, the low roll has resulted in poison exposure; it's now just a question of fleshing out precisely how that happens, and since that involves A) the poison being contact poison, and B) the PC wearing gloves, it's therefore going to involve the PC being exposed to that poison despite having worn gloves.There's a pretty big difference between the DM telling a player their character now has a greasy substance on their gloves, perhaps asking what if anything they do about that, and the DM saying that the character rubs their eye or picks their nose and now must make a saving throw due to contact poison. In the former case, the DM is narrating the result of the adventurer's action of touching the chest with a gloved hand. In the latter case, they are further describing what the character is doing, which is outside of the role of DM. The DM controls most of the game - do they really need to control the character, too?
There's nothing wrong with the PC describing that on their own, if they want. But I don't think the DM is inherently out of line if they narrate what that die roll constitutes from an in-game standpoint either.