It's a wild strawman that 'wearing a metal gauntlet for the last stage in order to counter a poison needle' equates to 'always say yes no matter what it is'.
You can always always always come up with a reason why something 'wouldn't work' or 'still needs a roll'. I think the quoted example is plausible and smart and I would certainly allow it.
I don't think it's wild to interpret "If every time players come up with this kind of idea you go with it, they are going to interact with their environment more and try to solve future problems creatively as well. Presumably, this is what you want." (underline added for emphasis) means always saying yes. It also clearly states that if you don't always "go with it" you're DMing wrong. I think always saying yes is a bad idea, having a conversation with the player and figuring out what they're trying to accomplish and talking alternatives is far better. Sometimes the answer will still be no, but they will know why the answer is no.
As I've said repeatedly whether the specific scenario would work is a DM judgement call. Gauntlets are never made completely of metal because they wouldn't work for holding a weapon, a player can't just declare otherwise. Even if they were made entirely of metal, they wouldn't provide the manual dexterity to trigger the trap in my opinion.
I'm talking general approach here. I will never be an "Always say yes" DM, that does not in any way harm or limit out of the box thinking.